Raman Spectroscopy and Polymorphism ALL GOOD MEASUREMENTS START at SQUARE ONE New Cuvette Holder Ensures Accurate, Repeatable Results

March 2019 Volume 34 Number 3 www.spectroscopyonline.com

Our 2019 Survey of Salaries, Workloads, and Job Satisfaction Trends in Analytical Spectroscopy Raman Spectroscopy and Polymorphism ALL GOOD MEASUREMENTS START AT SQUARE ONE New Cuvette Holder Ensures Accurate, Repeatable Results

Use the new Square One cuvette holder for absorbance or fluorescence. &XYHWWHVDQGOWHUVWWKHGHVLJQVQXJO\ to ensure accurate, repeatable results.

APPLIED SPECTRAL KNOWLEDGE • www.oceanoptics.com • [email protected] US +1 727-733-2447 • EUROPE +31 26-3190500 • ASIA +86 21-6295-6600 Expectations surpassed. Quality assured.

Unrivaled technology Milestone sets the standard for microwave Safety by design digestion excellence.

Maximum throughput You make important choices for your lab every day – decisions that can impact the quality of your analyses, the efficiency of your processes and Lower operating costs the reliability of your operation. With three decades of technology firsts, including over thirty patents, Milestone instruments offer the most innovative metals prep technology on the market today.

With a complete digestion product line that includes the revolutionary UltraWAVE and powerful Ethos UP, Milestone is the first choice of laboratories that rely on quality sample prep for superior ICP/ICP-MS analyses. See what Milestone can do for your lab. Learn more about Milestone digestion products at www.milestonesci.com or call us at 866.995.5100.

MILESTONE

Ethos UP UltraWAVE UltraCLAVE

MANUSCRIPTS: To discuss possible article topics or obtain manuscript preparation 485F US Highway One South, Suite 210 guidelines, contact the editorial director at: (732) 346-3020, e-mail: Laura.Bush@ Iselin, NJ 08830 ubm.com. Publishers assume no responsibility for safety of artwork, photographs, or (732) 596-0276 Fax: (732) 647-1235 manuscripts. Every caution is taken to ensure accuracy, but publishers cannot accept responsibility for the information supplied herein or for any opinion expressed. Michael J. Tessalone Vice President/Group Publisher SUBSCRIPTIONS: For subscription information: Spectroscopy, P.O. Box 6196, Duluth, MN [email protected] 55806-6196; (888) 527-7008, 7:00 a.m. to 6:00 p.m. CST. Outside the U.S., +1-218-740-6477. Stephanie Shaffer Delivery of Spectroscopy outside the U.S. is 3–14 days after printing. Single-copy price: Publisher U.S., $10.00 + $7.00 postage and handling ($17.00 total); Canada and [email protected] Mexico, $12.00 + $7.00 postage and handling ($19.00 total); Other Edward Fantuzzi international, $15.00 + $7.00 postage and handling ($22.00 total). Associate Publisher CHANGE OF ADDRESS: Send change of address to Spectroscopy, P.O. Box 6196, [email protected] Duluth, MN 55806-6196; provide old mailing label as well as new address; include ZIP Michael Kushner or postal code. Allow 4–6 weeks for change. Alternately, go to the following URL for Senior Director, Digital Media address changes or subscription renewal: http://ubmsubs.ubm.com/?pubid=SPEC [email protected] RETURN ALL UNDELIVERABLE CANADIAN ADDRESSES TO: IMEX Global Solutions, P.O. Box Laura Bush 25542, London, ON N6C 6B2, CANADA. PUBLICATIONS MAIL AGREEMENT No.40612608. Editorial Director [email protected] REPRINT SERVICES: Reprints of all articles in this issue and past issues are available (500 minimum). Licensing and Reuse of Content: Contact our official partner, Wright’s John Chasse Media, about available usages, license fees, and award seal artwork at Advanstar@ Managing Editor [email protected] wrightsmedia.com for more information. Please note that Wright’s Media is the only authorized company that we’ve partnered with for MultiMedia Healthcare materials. Jerome Workman, Jr. Senior Technical Editor C.A.S.T. DATA AND LIST INFORMATION: Contact Melissa Stillwell, (218) 740-6831; [email protected] e-mail: [email protected] Cindy Delonas INTERNATIONAL LICENSING: Jillyn Frommer, (732) 346-3007, Associate Editor fax: (732) 647-1104; e-mail:[email protected] [email protected] Kristen Moore Webcast Operations Manager

ecycled [email protected] R Pa % p 0 e r

0 Vania Oliveira e

- t

2 s 0 a Project Manager % W P r o e [email protected] st Consum Sabina Advani Digital Production Manager [email protected] © 2019 MultiMedia Healthcare LLC. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical including by Kaylynn Chiarello-Ebner Managing Editor, Special Projects photocopy, recording, or information storage and retrieval without permission in writing from [email protected] the publisher. Authorization to photocopy items for internal/educational or personal use, or the Dan Ward internal/educational or personal use of specific clients is granted by MultiMedia Healthcare LLC Art Director for libraries and other users registered with the Copyright Clearance Center, 222 Rosewood Dr. [email protected] Danvers, MA 01923, 978-750-8400 fax 978-646-8700 or visit http://www.copyright.com on- Brianne Pangaro line. For uses beyond those listed above, please direct your written request to Permission Dept. Marketing Associate fax 732-647-1104 or email: [email protected]. [email protected]

MultiMedia Healthcare LLC provides certain customer contact data (such as customers’ Melissa Stillwell names, addresses, phone numbers, and e-mail addresses) to third parties who wish to promote C.A.S.T. Data and List Information [email protected] relevant products, services, and other opportunities that may be of interest to you. If you do not want MultiMedia Healthcare LLC to make your contact information available to third parties for Thomas W. Ehardt President, MultiMedia Healthcare LLC marketing purposes, simply call toll-free 866-529-2922 between the hours of 7:30 a.m. and [email protected] 5 p.m. CST and a customer service representative will assist you in removing your name from MultiMedia Healthcare LLC lists. Outside the U.S., please phone 218-740-6477. Dave Esola VP & General Manager, Spectroscopy does not verify any claims or other information appearing in any of the adver- MultiMedia Healthcare LLC [email protected] tisements contained in the publication, and cannot take responsibility for any losses or other damages incurred by readers in reliance of such content. Jillyn Frommer Permissions Spectroscopy welcomes unsolicited articles, manuscripts, photographs, illustrations and [email protected] other materials but cannot be held responsible for their safekeeping or return. Jesse Singer To subscribe, call toll-free 888-527-7008. Outside the U.S. call 218-740-6477. Production Manager [email protected] Wendy Bong Audience Development Manager [email protected] Morgan Hight Audience Support Analyst [email protected] State-of-the-Art X-Ray Solutions •FAST SDD® •SDD •Si-PIN

In-house manufacturing = The highest performing detectors available

The best detector for optimal results Amptek Detector Comparison: Si-PIN, Standard SDD, and FAST SDD® 55Fe FWHM vs Peaking Time at 210 K 300

280 FAST SDD® Detector

260 25 mm2 Si-PIN >2,000,000 CPS and 122 eV FWHM Resolution

V 240 e k .9 220 13 mm2 Si-PIN Options: @ 5

M 2 2 200 • 25 mm collimated to 17 mm 2

FWH 6 mm Si-PIN e 2 2 F

55 180 • 70 mm collimated to 50 mm 160 25 mm2 • Windows: Be (0.5 mil) 12.5 μm, or C Series (Si N ) Standard SDD 3 4 140 25 mm2 FAST SDD® • TO-8 package fits all Amptek configurations 120 0 10 20 30 Tpeak (μs)

Confi gurations to meet your needs

XR-100 and PX5 Digital Pulse Processor X-123 Complete X-Ray Spectrometer XRF Experimenters Kit

OEM Confi gurations

A sample of detectors with preamplifi ers Digital Pulse Processors and Power Supplies and heat sinks

® For XRF amptek.com 6 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

v 34 n 3 CONTENTS m 2019 ® COLUMNS March 2019 Volume 34 Number 3 Molecular Spectroscopy Workbench ...... 10 Raman Spectroscopy and Polymorphism David Tuschel The differentiation of polymorphs is important, particularly in the pharmaceutical industry. We demonstrate the practicality of using Raman spectroscopy to differentiate crystal forms for polymorph characterization and screening, and explain aspects of chemical bonding and solid state structure that affect the Raman spectra of crystal lattice vibrational modes.

IR Spectral Interpretation Workshop ...... 22 Organic Nitrogen Compounds II: Primary Amines Brian C. Smith Amines, which contain carbon, hydrogen, and nitrogen, come in six varieties, but using the N-H stretching peak positions by themselves will distinguish between all the different amine types.

Spectroscopy Spotlight ...... 45 The LIBS Advantage in Mining and Energy Applications Laura Bush Cover image courtesy of Laser-induced breakdown spectroscopy (LIBS) has seen significant expanded adoption in 3D generator/AdobeStock. recent years, particularly in industrial applications where it can provide important advantages over other techniques. Mohamad Sabsabi, of the National Research Council of Canada, has been leading programs to research and implement the use of LIBS in mining and energy applications.

ON THE WEB ARTICLES

WEB SEMINARS 2019 Salary Survey: Some Unusual Trends ...... 26 Jerome Workman, Jr. Ensuring Integrity of Drug Formula- Our annual salary and employment survey looks at salaries, workload, job satisfaction, and tion from Development to QC the overall job market for spectroscopists. This year, we had some surprising results. Katherine Paulsen and Mike Garry, Sr., Thermo Fisher Scientific Trends in Spectroscopy: A Snapshot of Notable Advances and Applications . . . . 36 ICP-OES Technology Advancements Michael MacRae Addresses the Axial/Radial Dilemma Spectroscopic measurement factors into every facet of modern life. Here, we survey on Plasma Viewing While Offering noteworthy recent advances in and applications of atomic and molecular spectroscopy, Improvements in Overall Performance touching on their uses in fields such as biomedicine, materials science, environmental Olaf Schulz, Spectro Analytical Instruments monitoring, agriculture, pharmaceutical research, public safety, and more.

Re-think Quantitative Analysis: Solu- tions for Challenging Measurements DEPARTMENTS Adam J. Hopkins and Elena Hageman, News Spectrum ...... 9 Metrohm USA Calendar ...... 49

The Role of Raman Spectroscopy in Short Courses ...... the QA/QC Laboratory 50 Tom Tague, Bruker Corporation Products and Resources ...... 52

spectroscopyonline.com/spec/webcasts Ad Index ...... 54

Like Spectroscopy on Facebook: Spectroscopy (ISSN 0887-6703 [print], ISSN 1939-1900 [digital]) is published monthly by MultiMedia Healthcare LLC 325 W 1st St STE www.facebook.com/SpectroscopyMagazine 300 Duluth MN 55802. Spectroscopy is distributed free of charge to users and specifiers of spectroscopic equipment in the United States. Follow Spectroscopy on Twitter: Spectroscopy is available on a paid subscription basis to nonqualified readers at the rate of: U.S. and possessions: 1 year (12 issues), https://twitter.com/spectroscopyMag $74.95; 2 years (24 issues), $134.50. Canada/Mexico: 1 year, $95; 2 years, $150. International: 1 year (12 issues), $140; 2 years (24 issues), $250. Periodicals postage paid at Duluth, MN 55806 and at additional mailing offices. POSTMASTER: Send address changes to Spec- Join the Spectroscopy Group on LinkedIn troscopy, P.O. Box 6196, Duluth, MN 55806-6196. PUBLICATIONS MAIL AGREEMENT NO. 40612608, Return Undeliverable Canadian http://linkd.in/SpecGroup Addresses to: IMEX Global Solutions, P. O. Box 25542, London, ON N6C 6B2, CANADA. Canadian GST number: R-124213133RT001. Printed in the U.S.A.

8 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com Editorial Advisory Board

Fran Adar Horiba Scientific Rachael R. Ogorzalek Loo University of California Los Angeles, David Geffen School of Medicine Russ Algar University of British Columbia Howard Mark Mark Electronics Matthew J. Baker University of Strathclyde R.D. McDowall McDowall Consulting Ramon M. Barnes University of Massachusetts Gary McGeorge Bristol-Myers Squibb Matthieu Baudelet University of Central Florida Linda Baine McGown Rensselaer Polytechnic Institute Rohit Bhargava University of Illinois at Urbana-Champaign Francis M. Mirabella Jr. Mirabella Practical Consulting Solutions, Inc. Paul N. Bourassa Blue Moon Inc. Ellen V. Miseo Illuminate Michael S. Bradley Thermo Fisher Scientific Michael L. Myrick University of South Carolina Deborah Bradshaw Consultant John W. Olesik The Ohio State University Lora L. Brehm The Dow Chemical Company Steven Ray State University of New York at Buffalo George Chan Lawrence Berkeley National Laboratory Jim Rydzak Specere Consulting John Cottle University of California Santa Barbara Jerome Workman Jr. Biotechnology Business Associates David Lankin University of Illinois at Chicago, Lu Yang National Research Council Canada College of Pharmacy

Barbara S. Larsen DuPont Central Research and Development Spectroscopy’s Editorial Advisory Board is a group of distinguished individuals assembled to help the publication fulfill its editorial mission to promote the effective use of spectroscopic technology as a practical research and measurement tool. Bernhard Lendl Vienna University of Technology (TU Wien) With recognized expertise in a wide range of technique and application areas, board members perform a range of functions, such as reviewing manuscripts, suggesting Ian R. Lewis Kaiser Optical Systems authors and topics for coverage, and providing the editor with general direction and feedback. We are indebted to these scientists for their contributions to the publication and to the spectroscopy community as a whole.

Next generation Raman imaging

High performance Raman systems for a range of applications

Raman spectroscopy produces chemical and structural images to help you understand more about the material being analysed. Renishaw has decades of experience developing flexible Raman systems that give reliable results, for even the most challenging measurements. With Renishaw’s suite of Raman systems, you can see the small things, the large things and things you didn’t even know were there. Visit www.renishaw.com/raman

Renishaw Inc. 1001 Wesemann Drive, West Dundee, Illinois, 60118, United States T +1 847 286 9953 F +1 847 286 9974 E [email protected] www.renishaw.com www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 9 News Spectrum Spectral Imaging Improves Plastics Recycling Steve Buckley Joins Ocean Optics To reduce the quantity Steve Buckley has joined Ocean Optics as the vice of plastics that are president of product development and engineering. dumped into the He will lead the Ocean Optics engineering and product environment, efficient development teams globally with a focus on the recycling is essential. delivery of next-generation optical sensing systems But many plastics and solutions. cannot be economically Buckley’s career in photonics engineering and sorted for recycling, development started in academia. Ten years of and sorting plastics technology leadership in entrepreneurial ventures and that contain flame Near infrared hyperspectral imaging of businesses followed. Today, Buckley is focused on retardants is particularly samples of plastics and their classifi cation spectroscopy coupled with intelligent analysis systems as a function of type of fl ame-retardant: important. Plastics 1,2,5,6,9,10-hexabromo-cyclododecane, to gain solutions in areas such as biochemistry and that contain flame HBCD (red samples); 3,5-tetrabromo- industrial materials analysis. Most recently, Buckley was retardants to increase bisphenol A, TBBPA (yellow samples); the CEO of Flash Photonics, of Redmond, Washington, their resistance to pentabromophenyl ether, deca-BDE and the CEO of Lightspeed Microscopy, a start-up in (green samples); and reference, (blue ignition, reduce samples). Seattle, Washington. He currently writes the “Lasers & flames spreading, Optics” column for Spectroscopy magazine. minimize smoke formation, and prevent the plastic Buckley studied mechanical and aerospace from dripping can vary considerably in the amount engineering at Princeton University (Princeton, New and type of flame retardant that is added to them, Jersey), and earned his PhD in mechanical engineering because of the need to tailor the plastic to its from the University of California Berkeley. particular application and to meet safety standards. Buckley will be based in Redmond, Washington. ◾ Before recycling can occur, plastics require sorting by type and by flame retardant added. Without sorting, recycling cannot take place. In a paper published in the Journal of Spectral SPECIAL ISSUE HIGHLIGHTS Imaging, José Amigo at the University of Copenhagen, Denmark, and colleagues describe a method that ADVANCES IN PORTABLE AND uses near-infrared (NIR) hyperspectral imaging and ® HANDHELD SPECTROSCOPY chemometrics to sort plastics that contain different This special supplement from November 2018 Volume 33 Number s11 www.spectroscopyonline.com Spectroscopy types of plastic and plastics that contain different presents articles with expert advice on the following topics: additions of flame retardants (1). By using an imaging technique, the approach • Handheld Raman, Mid-Infrared and Near Infrared Spectrometers: developed by Amigo can be used during the plastics State-of-the-Art Instrumenta- sorting on a conveyor belt in a recycling plant. ADVANCES IN tion and Useful Applications PORTABLE AND HANDHELD The method discussed in the paper uses a decision SPECTROSCOPY Handheld Raman, mid-infrared, and tree chemometrics approach combined with spectral near infrared spectrometers have launched vibrational spectroscopy data obtained from NIR hyperspectral imaging and into a new era of in-the-field and on-site analysis. We assess is able to distinguish between different plastics and the technological developments that have led to this progress. flame retardants within them with 100% accuracy. Although sorting of recycling plastics has been • Portable, High-Efficiency Transmission Raman Spectroscopy for At-Line Content Uniformity Testing of studied for many years, Amigo wanted to take that Pharmaceutical Tablets process a step further and make it possible to separate Portable transmission Raman spectroscopy, combined with plastics by flame retardant. They also tested the chemometric modeling, is quickly emerging as a valued technique to be practical. “Moreover,” said Amigo, “the technique for content-uniformity testing. proposed methodology was tested with real samples • Portable Spatially Offset Raman Spectroscopy for Rapid that can be found in current recycling lines.” Hazardous Materials Detection Within Sealed Containers This technique has been successfully used by the military, fi rst responders, and customs and law enforcement operators to detect explosives, chemical agents, precursors Reference and hazardous narcotics. (1) D. Caballero, M. Bevilacqua, and J.M. Amigo, J. Spectral Imaging 8, a1 (2019). https://doi. http://www.spectroscopyonline.com/ org/10.1255/jsi.2019.a1 special-issues-11-02-2018 10 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

Molecular Spectroscopy Workbench Raman Spectroscopy and Polymorphism

Single crystals can be formed that have different unit cells. Crystal polymorphism is the formation of a compound in various crystallographic forms. The differentiation of polymorphs is important, particularly in the pharmaceutical industry. Raman spectroscopy has emerged as a complementary method to X-ray diffraction, the “gold standard” for characterization of crystal structure. Different crystal forms of ionic or covalent solids and molecular crystals can be differentiated through Raman spectroscopy. The Raman spectra of molecular crystals consist of bands attributable to external and internal crystal lattice vibrational modes. We discuss these aspects of chemical bonding and solid state structure that affect the Raman spectra of crystal lattice vibrational modes, and demonstrate the practicality of using Raman spectroscopy to differentiate crystal forms for polymorph characterization and screening.

David Tuschel

olymorphism is a term used in various scientific Raman spectra of that compound’s specific crystal forms. disciplines with different meanings. Here, we use Raman spectroscopy is often found to be experimentally P it to describe the multiplicity of phases or crystal more convenient to use than X-ray diffraction for poly- structures of a single compound. Crystal polymorphism is morph characterization or screening. Reference Raman the formation of a compound in various crystallographic spectra of a compound’s polymorphs can be reliably used forms; that is, single crystals can be formed that have dif- to confirm crystal forms, or even to identify new ones in ferent unit cells. The differentiation of polymorphs is im- a research setting or in polymorph screening. The most portant, particularly in the pharmaceutical industry. The important aspect of Raman spectroscopy when applying it crystal form of an active pharmaceutical ingredient can to polymorph analysis is spectral resolution. That is con- affect its chemical or physical stability, and its dissolution sistent with the fact that high spectral resolution is also rate. Consequently, the crystal structure of a pharmaceuti- required to differentiate crystal forms by X-ray diffraction. cal compound can have a profound effect on its efficacy The Raman spectrometer must have spectral resolution and potency. Of course, to analyze crystal structure, X-ray sufficient to resolve the smallest differences in energies of diffraction is considered the “gold standard” for charac- the crystal lattice vibrational modes, which are affected by terizing and differentiating crystal forms of compounds. changes in molecular interactions arising from different However, once different phases of a chemical compound unit cell structures or configurations of the molecules, or have been confirmed or newly identified by X-ray diffrac- formula units within the unit cell. Just as small differences tion, those same samples can be used to generate reference in a compound’s crystal structure lead to small differences www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 11 in the X-ray diffraction pattern, the ing the different types of crystal lattice defined as a crystal lattice vibrational Raman spectra of crystals with small vibrational modes from which they wave propagating through the crystal differences in bond lengths or crys- originate and comparing their suitabil- arising from repetitive and systematic tal spacing will manifest small differ- ity for distinguishing crystal forms. To atomic displacements. It should also be ences in the Raman peak positions. appreciate why Raman spectroscopy is understood that these displacements are Hence, just as high resolution X-ray sensitive to crystal structure, we need to quantized vibrations of the atoms in the diffraction is needed to resolve poly- understand the origins of Raman scat- crystal lattice and are travelling waves. morphs, so too is high spectral reso- tering from solid state materials. Raman The phonon has the characteristics of a lution required to differentiate crystal scattered photons are generated in solid travelling wave insofar as it has a propa- forms by Raman spectroscopy. state materials through the creation or gation velocity, wavelength, wave vector, Many spectroscopists are chem- annihilation of phonons which corre- and frequency. It is important to note that ists, and therefore most likely learned spond to Stokes and anti-Stokes Raman all of the peaks in a Raman spectrum of vibrational spectroscopy as molecular scattering, respectively. A phonon is a crystalline solid are attributed to pho- spectroscopy. If you are a chemist, you learned about the normal vibrational modes of discrete molecules, as op- posed to solid state materials, and their Raman or infrared activity based upon molecular spectroscopic selection rules. Raman spectra of compounds in the liquid or vapor phase consist of narrow bands whose widths depend upon the degree of chemical interaction between the molecules. The weaker the chemical interaction, the narrower the band will be. In fact, the bands of a compound in the vapor phase will be narrower than those of the same compound in the liquid phase for the very reason that the molecular interactions are weaker (1). The broad infrared absorption and Raman bands of water demonstrate the effect of hydrogen bonding and the result of different degrees of chemical interaction between the molecules in a neat liquid. The breadth of the O-H stretching modes in particular is a manifestation of the distribution of vibrational energy states as a result of these many and different chemical interactions. 3D Raman image of a pharmaceutical ointment. Those same molecular interactions can affect the vibrational spectrum of a compound in the solid state, and are dependent upon how the molecules are configured or 3D Ram oriented in the unit cell. gg Interpreting the Raman spectra of compounds or materials in the solid Turn ideas into discoveries state requires the knowledge of concepts and mathematical treatments other than Let your discoveries lead the scientiﬁ c future. Like no other those of molecular spectroscopy. The system, WITec’s confocal 3D Raman microscopes allow for purpose of this installment of “Molecu- cutting-edge chemical imaging and correlative microscopy lar Spectroscopy Workbench” is to dem- with AFM, SNOM, SEM or Proﬁ lometry. Discuss your ideas with us at [email protected]. onstrate the use of Raman spectroscopy for differentiating polymorphs, and to explain the underlying bases for that capability. In particular, we examine Raman AFM SNOM RISE www.witec.de and discuss the low and high frequency regions of a Raman spectrum, explain- MADE IN GERMANY 12 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

nons, and not only those at low energy or Raman shift. P.M.A. Sherwood makes that point clear in his fine book Vibra- tional Spectroscopy of Solids: “All crystal vibrations involve the entire lattice and are thus lattice vibrations (a term some- times unfortunately only applied to external vibrations) and such vibrations can be considered as a wave propagating through the crystal lattice” (2). Unlike the normal vibrational mode of an individual molecule, a phonon is a crystal lattice vibrational wave travelling through the crystal. This is why a mathematical treatment of the vibrational motions of the crystal’s atoms must take into account the medium through which Figure 1: Raman spectra of the rutile (red) and anatase (blue) crystalline forms of titanium the phonon is propagating, and why the dioxide (TiO ). 2 energy of the phonon depends upon the configuration of the atoms and chemical bonds within the unit cell. In chemistry courses, we learn about Raman scattering through the interaction of light with molecules. A molecule, initially in the ground state, interacts with an incident photon driv- ing the molecule to a virtual energy state whereupon it drops to the first excited vibrational state and emits a photon (Stokes Raman scattering). The energy difference between the incident and scattered photons is equal to the energy difference between the ground and first excited vibrational states. Had the molecule initially been in the first excited vibrational Figure 2: Raman spectrum obtained from a grain of anatase titanium dioxide (TiO2) with an impurity phase of rutile present (green). The Raman spectra of reference rutile and anatase state and ended in the ground state, phases are shown in red and blue, respectively. a quantum of energy would have been transferred from the molecule to the scattered photon, and its energy would have been greater than that of the incident photon (anti-Stokes Raman scattering). Hence, one can observe the Raman spectrum at either longer (Stokes) or shorter (anti-Stokes) wave- lengths relative to that of the incident monochromatic laser beam. When dealing with gases or liquids, it is appropriate to speak of the interaction of a photon with individual molecules. However, very often we deal with solid state materials for which there may be no molecular spe-

cies, such as titanium dioxide (TiO2), silicon (Si), carbon (C, graphene or Figure 3: Raman spectrum obtained from a grain of rutile titanium dioxide (TiO2) with an diamond), or calcium carbonate impurity phase of anatase present (green). The Raman spectra of reference rutile and anatase (CaCO3). Raman spectroscopy of solid phases are shown in red and blue, respectively. state materials involves the inelastic www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 13 scattering of light by phonons, quanta that have the energy of crystal lattice vibrations. The Stokes and anti-Stokes Raman scattering consists of the generation or annihilation of a phonon in the solid, respectively. In crystalline materials, the phonons can be understood as crystal lattice vibrational modes whether the crystal is a covalent or ionic solid or a molecular crystal such as TiO2, barium fluoride (BaF2), or water (H2O, ice), respectively. When speaking of Raman spectra of Figure 4: Raman spectra obtained from grains of paracetamol form I (red) and form II (blue). solid state materials, some spectroscopists will describe certain bands as pho- collectively in an ice crystal. Some low en- of long range translational symmetry nons, and others as molecular vibrations. ergy Raman bands are a result of shear or that is present in a crystal. The internal Strictly speaking, this is not correct. All of interlayer breathing modes of the crystal crystal lattice vibrational modes arise the bands in a Raman spectrum of a solid layers. The shear modes can be pictured from the coupling through the crystal arise from phonons. A more appropriate as atomic or molecular layers moving of the local vibrational modes observed distinction is to speak of external and antiparallel to each other within their for the molecular species. We can think internal crystal lattice vibrational modes respective planes, whereas the breathing of these types of phonons as collective when speaking of solid state Raman band modes involve the layers moving away local modes modified through coupling assignments, particularly for molecular from and towards each other. The exter- with other molecules in the crystal and crystals (2). An external crystal lattice vi- nal crystal lattice vibrations are generally affected by their arrangement in the crys- brational mode can be thought of as the of low energy, and, of course, would be tal lattice. Their Raman shifts are often collective motion of molecules as a whole, absent from the liquid or gas spectrum similar but not identical to those of the such as whole water molecules moving of the material because of the absence molecular (liquid or gas) spectrum. 14 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

tice modes. Perhaps less well known is the sensitivity of the external modes to molecular interactions, such as hydrogen bonding or even the weaker van der Waals forces between molecules, or formula unit layers within the crystallographic unit cell. This sensitivity to the chemical interactions results in the energies of the external modes, and therefore their Raman peak positions, being strongly affected by the configurations of molecules or formula units within the unit cell. We present and discuss the

Raman spectra of TiO2, paracetamol, and carbamazepine to demonstrate the merits of using Raman spectroscopy to Figure 5: Raman spectra obtained from different grains of paracetamol form I. differentiate crystal forms for polymorph characterization and screening.

Anatase and Rutile TiO2 There are multiple crystalline phases

of TiO2, and the ones with which you may be the most familiar are anatase (tetragonal), rutile (tetragonal), and brookite (orthorhombic). Of these three, the two most commonly en- countered in an industrial setting are anatase and rutile. Anatase belongs

to the crystal class of D4h, with four formula units per crystallographic unit cell. The correlation method for vibrational selection rules predicts six Raman active modes (A + 2 B + 3 Figure 6: Raman spectra obtained from different grains of paracetamol form II. 1g 1g Eg) for anatase TiO2 (3,4). Rutile TiO2 also belongs to the crystal class of D4h, but has two formula units per crystallographic unit cell. The correlation method predicts four Raman active

modes (A1g + B1g + B2g + Eg) for rutile TiO2 (3,5). Clearly, then, one should in principle be able to differentiate the

anatase and rutile phases of TiO2 by Raman spectroscopy just by applying the Raman polarization selection rules to identify the symmetry species of Raman bands and by the total number of bands observed in the Raman spectrum. Nevertheless, the application of group theory and Raman polarization Figure 7: Raman spectra obtained from grains of paracetamol form I (red) and form II (blue). selection rules for the purpose of identifying or differentiating crystal forms As you may expect, the external lattice the characterization and screening of is not always straightforward. vibrational modes or low energy phonons polymorphs. In addition, Raman spec- Group theory and the correlation are very sensitive to crystal structure. tra of low energy phonons are dependent method are beneficial for identify- That is why the low frequency region of upon the crystal orientation with respect ing Raman active modes and assign- the Raman spectrum has proven so use- to the incident laser polarization as are ing a symmetry species to a particu- ful in the pharmaceutical industry for the higher energy internal crystal lat- lar band, but they do not predict the www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 15

Raman scattering strength of the individual crystal lattice vibrational modes. Furthermore, second order modes can also appear in the Raman spectrum, thereby complicating the assignment of symmetry species and the total count of bands attributed to fundamental lattice vibrational modes appearing in a spectrum. The Raman spectra of anatase and rutile TiO2 are shown in Figure 1 (These spectra and all the others shown in this publication were acquired using 532 nm ex- Figure 8: Raman spectra obtained from grains of paracetamol form I (red) and form II (blue). citation and a long working distance 50X Olympus microscope objective). spectrum, there is a very weak band scattering. The lesson to be learned is The rutile spectrum consists of four at 828 cm-1 which has been assigned that the interpretation of even as sim- bands as predicted by the correlation to the B2g symmetry species. All four ple a spectrum as that of rutile TiO2 is method. The bands at 143, 445, and of the fundamental lattice vibrational not straightforward, and we are aided -1 610 cm have been assigned to the B1g, modes are now accounted for. You in our assignments and interpreta- Eg and A1g symmetry species, respec- will also notice a broad shoulder at tion by previously published work. It tively (6). However, the broad band at approximately 707 cm-1 which can is helpful to apply group theory and 241 cm-1 has been attributed to second- be attributed to two-phonon Raman the correlation method when perform- order or two-phonon Raman scatter- scattering. Although one might have ing crystallographic studies by Raman ing, and so cannot be counted among expected a simple spectrum consisting spectroscopy, but be sure to consult the four fundamental modes predicted of four bands based upon group theory previously reported results in order to by group theory (6). Where then is the analysis and the correlation method, perform a thorough study and make fourth fundamental mode? Although a total of six bands are present, two of the most accurate band assignments barely discernable in the rutile TiO2 which are due to second order Raman and interpretations of spectra.

Elevate your research with Wiley spectral libraries

&RQGHQWLGHQWLFDWLRQZLWKWKH 1(:6LJPD$OGULFKFROOHFWLRQ

*Sigma-Aldrich is now Millipore Sigma

)RUPRUHLQIRUPDWLRQYLVLW sciencesolutions.wiley.com Ȃ 16 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

at temperatures below 73 K (6). And so, with a little work involving group theory, the correlation method and study of the literature we are able to assign the Raman bands, and differentiate the anatase and rutile forms

of TiO2 by their distinctly different spectra. Taken together, we see that the key to differentiating these two polymorphs is the peak positions and relative intensities of the two crystal forms. However, as we will see when discussing the Raman spectra of the molecular crystals paracetamol and carbamazepine, one must be cautious Figure 9: Raman spectra obtained from grains of paracetamol form I (red) and form II (blue). and not over interpret the significance of different relative intensities. The analysis of different grains of the same crystal form of a compound can produce spectra of vastly different relative intensities, which can lead the spectroscopist to incorrectly conclude that the grains are of different crystal forms. The differences in peak positions are far more reliable than different relative intensities for differentiating crystal forms. It is also important to keep in mind that samples of a single compound may not necessarily consist of a single phase or crystal form. One may find, even on a scale of only a few microm- Figure 10: Raman spectra obtained from grains of carbamazepine form I (red) and form III (blue). eters, mixtures of crystalline phases. For example, a spectrum shown in Figure 2 was acquired from a grain

that is nominally anatase TiO2 but its spectrum is comprised of bands attributable to both the anatase and rutile phases. In spite of the fact that the beam diameter is less than several micrometers, the spectrum consists of contributions from two phases. Clearly, crystallographic domains or grain sizes can be very small, and so one must be aware of this fact even when performing micro-Raman spectroscopy. The bands at 143, 197, 397, 516 and 638 cm-1 are those expected

for anatase TiO2. However, the bands at 445 and 610 cm-1 very clearly corre- Figure 11: Raman spectra obtained from different grains of carbamazepine form III. spond to those of our reference rutile -1 The total number of bands observed (B1g), and 638 cm (Eg) (6). Those five phase, thereby leading us to conclude in the anatase TiO2 spectrum of Fig- assignments account for all but one that the sample is not purely anatase, ure 1 is only five, whereas six are pre- A1g band. According to Tompsett and in spite of the fact that it was labeled dicted. The bands and their symmetry coworkers, the missing A1g band ap- as only anatase. In fact, with our mag- -1 -1 species assignments are 143 cm (Eg), pears at 507 cm and can only be re- nified intensity scale in Figure 2, one -1 -1 -1 -1 197 cm (Eg), 397 cm (B1g), 516 cm solved from the 516 cm (B1g) band can detect weak contributions at 445 www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 17

-1 and 610 cm in our anatase TiO2 refer- and no individual TiO2 molecules crystals. The Raman spectrum of a ence spectrum, thereby indicating that exist at standard temperature and molecular crystal will be similar, but our anatase reference material may not pressure, the common pain reliever not identical, to that of the molecular be entirely pure. Another possible in- paracetamol is a molecular crystal (liquid or vapor phase) spectrum of terpretation of the middle spectrum consisting of molecules in the crys- the same compound. Those bands in in Figure 2 is that it may indicate the tallographic unit cell. Paracetamol is the Raman spectrum of a molecular presence of the brookite phase of TiO2. a solid at room temperature, but, if crystal that are similar to those found However, the brookite phase TiO2 heated and melted, will form a liquid in the molecular spectrum of the spectrum has many more bands than consisting of paracetamol molecules. same compound in either the liquid the middle spectrum, and the peak That is not the case for TiO2. There or vapor phase are attributed to inter- positions are not a good match (6). are significant differences between nal phonon modes. The designation Therefore, we can reasonably conclude the vibrational spectra of ionic or co- internal phonon mode arises from the that the sample is primarily anatase valent solids and those of molecular approximation of those crystal lattice

TiO2 with some rutile TiO2 present. To further emphasize the need to be aware of the presence of multiple forms or impurity phases, consider the spectrum in Figure 3 from a sample labeled as rutile TiO2. As expected, the rutile bands at 241, 445, and 610 cm-1 are present. However, we see unexpectedly strong Raman scattering at 143 cm-1, and bands at 197, 397, 516, and 638 cm-1, which can be attributed to the anatase form of TiO2. Of course, the contributions of the signal strengths of the two phases are directly proportional to their relative amounts, and it would appear that the spectral contri- bution of the impurity phase is greater here than that in Figure 2. However, caution is necessary if one is to use the relative signal strengths to perform even a semi-quantitative analysis of a sample consisting of multiple phases. Reference spectra of the pure phases would be required, and the optical All New QTRam® experimental conditions for sample laser illumination and light collection Portable Raman System for should be comparable, if not identical, in order to accurately perform a Content and Blend Uniformity semi-quantitative mixture analysis. Also, don’t forget the importance of Nondestructive quantitative transmission the sample shape and size. A single crystal with a flat surface oriented in a Raman analysis of solid dosage forms particular plane relative to the incident laser polarization will yield a spectrum over a large sample volume. of quite different relative intensities compared to that of a polycrystalline No sample preparation, no solvents, with grain of the same crystalline phase. It would be very difficult to perform an results in seconds. accurate quantitative mixture analysis if the grain morphology closely ap- proximated that of a single crystal. www.bwtek.com/NewQTRam Paracetamol Forms I and II

Whereas TiO2 is a covalent solid 18 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

nal phonon modes can be affected by near neighbor chemical interactions depending upon the arrangements of the molecules within the unit cell. Consequently, crystal structures with different configurations of the molecules within the unit cell will manifest different molecular interactions, thereby affecting the energies of the crystal lattice vibrational modes, including the internal phonon modes. That is the reason for the differences in Raman spectra of polymorphs of a molecular crystal. The energies of the crystal lattice vibrational modes Figure 12: Raman spectra obtained from grains of carbamazepine form I (red) and form III (blue). depend upon the configuration of the molecules within the crystallographic unit cell, and, in particular, their molecular interactions. As discussed in the introduction, the external crystal lattice vibrational modes are those involving the collective oscillation of entire molecular species within the unit cell and propagating through the crystal. These collective oscillations of entire molecules can consist of shear modes, so-called interlayer breathing modes (wherein the molecules move towards and away from each other), and bending modes (where the angle between molecules varies). As you might expect, these lattice vibrational modes are at low Figure 13: Raman spectra obtained from grains of carbamazepine form I (red) and form III (blue). frequency, typically less than 100 cm-1, and as low as 5 cm-1, because of the higher mass of the collective move- ments of entire molecules within the unit cell. This region of the vibrational spectrum corresponds to the terahertz frequencies when performing infrared absorption spectroscopy. The frequencies of the external vibrational modes are very sensitive to the molecular arrangements within the unit cell. Consequently, the external crystal lattice vibrational modes are generally the most sensitive to crystal form, and the most beneficial for differentiating polymorphs. We will compare the efficacy of the internal and external crystal lattice Figure 14: Raman spectra obtained from grains of carbamazepine form I (red) and form III (blue). vibrational modes for characterizing and vibrational modes being associated the atom–bond or bond–bond molec- differentiating polymorphs in the fol- with the functional groups or struc- ular interactions within the unit cell lowing discussions of Raman spectra of tural units (tetrahedra or octahedra) perturb the energetics of the bonds, paracetamol and carbamazepine. of the molecule and their stretching or and thereby affect the vibrational Spectra consisting of bands due to ex- angle bending of local bonding in the frequencies of those internal phonon ternal and internal crystal lattice vibra- molecule. When a crystal is formed, modes. The energies of even the inter- tional modes of the fingerprint region www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 19 acquired from two forms of paracetamol So where does this leave us? How are we and II, respectively. You may have heard are shown in Figure 4. Note how simi- to confidently apply Raman spectroscopy that the lower the frequency of the crys- lar the spectra of forms I and II are at to characterize and differentiate poly- tal lattice vibrational mode is the more Raman shifts greater than 200 cm-1, morphs of molecular crystals if the spectra sensitive it will be to crystal structure. whereas they appear quite different obtained from different grains of the same Whereas that statement is generally between 10 and 200 cm-1. Of course, crystal form can appear different? This is true when applied to a comparison of what we have in mind in making that where the spectral resolution of the Raman external and internal crystal lattice vi- statement is the apparent similarity of spectrometer is so important. We start by brational modes as a group, it is not nec- the approximate band positions and analyzing and comparing the peak posi- essarily true when applied within those the relative intensities of the two spec- tions of the Raman spectra of paracetamol two classifications, as we can clearly see tra. One might therefore incorrectly forms I and II at the higher frequencies of from high and middle frequency por- conclude from Figure 4 that merely ex- the fingerprint region shown in Figure tions of the fingerprint region shown in amining the low frequency portion of 7. The spectra are indeed similar as one Figures 7 and 8, respectively. The lesson the spectrum is all that is necessary to would expect, because they are spectra to be learned here is that the difference distinguish polymorphs, and that the from molecular crystals of the same com- in peak position with respect to crystal high frequency region is not helpful in pound. However, they do not have exactly form is dependent upon how the dif- differentiating crystal forms. However, the same peak positions because the ener- ferent crystal structures affect the mo- viewing the spectra of forms I and II in gies of their corresponding phonons are lecular interactions within the crystallo- this fashion for purposes of comparison different due to slightly different crystal graphic unit cell and thereby determine can be a little deceptive. We shall see structures. For example, there is a 6 cm-1 the energies of the crystal lattice vibra- that, when viewed on a different scale, difference between the 1619 and 1625 tional modes. If there is little difference the actual peak positions of forms I and cm-1 bands in forms I and II, respectively. between the unit cell structures of two II are not exactly the same for the two Furthermore, note how very different the crystal forms, then the differences in the forms, and that the bands from internal band structures (peak positions and rela- energies of their phonon modes and cor- phonon modes can be effectively used to tive intensities) of the two forms are in the responding Raman peak positions will differentiate polymorphs. 1200 to 1300 cm-1 region. In fact, most of also be very small. Therefore, the ability An important consideration in spec- the corresponding bands in the spectra of to differentiate molecular crystal forms tral interpretation is the optical sam- the paracetamol forms I and II have differ- based upon the peak positions of inter- pling of the spectral acquisition. This ent positions to a greater or lesser degree nal crystal lattice vibrational modes will is critically important particularly if in the region from 1100 to 1700 cm-1. The be determined by the spectral resolution performing micro-Raman spectros- exception is the band at 1169 cm-1 which of the Raman spectrometer. copy where the orientation of individual is the same for both forms. And so, with Turning now to an evaluation of sample grains relative to the direction adequate spectral resolution, one can read- the external crystal lattice vibrational and polarization of the incident laser ily differentiate paracetamol forms I and II modes, we examine the spectra of beam can have significant effects on based upon the peak positions of high fre- paracetamol forms I and II in the re- the acquired spectrum. For example, quency internal crystal lattice vibrational gion from 10 to 250 cm-1 shown in compare the spectra shown in Figure 5 modes. In general, the polymorphs of mo- Figure 9. Here we see significant dif- acquired in the same spectral region of lecular crystals can be differentiated even ferences in the peak positions and 10 to 1750 cm-1 from different grains of at the high frequencies of the fingerprint relative intensities of bands from these paracetamol form I. These spectra, al- spectral region if the Raman spectrometer two crystal forms. None of the bands though acquired from different grains has a spectral resolution of 1 cm-1 or better. in this spectral region appear to have of the same crystal form, appear more The trend observed in the high fre- counterparts at the same Raman shift dissimilar than the spectra obtained quency fingerprint spectral region is in the other crystal form spectrum; the from the two different crystal forms observed even in the region from 300 to band structures appear almost entirely shown in Figure 4. If one were not care- 700 cm-1, as shown in Figure 8. Keep in different. However, remember that it is ful, one might incorrectly conclude that mind that the bands appearing in this not primarily the relative intensities of the spectra in Figure 5 were acquired middle frequency fingerprint region the bands that are to be relied upon to from two different crystal forms. Like- also arise from internal crystal lattice differentiate the crystals forms but their wise, the spectra shown in Figure 6 were vibrational modes just as do the bands peak positions due to the energies of acquired from different grains of form II observed in Figure 7. The band struc- the external crystal lattice vibrational paracetamol. The spectra appear quite tures are even more similar in this mid- modes. The differences in the relative similar at Raman shifts greater than dle frequency portion of the fingerprint intensities of the Raman bands in the 200 cm-1 as we would expect. However, spectral region. However, if one were low frequency portion of the spectra below 200 cm-1 the band structures ap- restricted to only this segment of the acquired from different grains of the pear quite different, and one might in- spectrum, the corresponding bands at same crystal forms shown in Figures 5 correctly conclude that the spectra were 466 and 454 cm-1 could quite readily be and 6 make clear that different relative acquired from different crystal forms. used to differentiate paracetamol forms I signal strengths cannot be relied upon 20 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com to differentiate polymorphs. Rather, the cm-1. The band structures arising from 0, and -3 cm-1, respectively. Obviously, energies of the external crystal lattice both the external and internal crystal the more differences in Raman band vibrational modes and not their relative lattice vibrational modes appear suf- peak positions that are measured, the signal strengths differentiate the crys- ficiently different such that one might more thorough the characterization of tal forms. Even small differences in the incorrectly conclude from the spectra or screening for polymorphs will be. Of configuration of molecules within the that the carbamazepine samples were course, one could simply compare the crystallographic unit cell can significantly of different crystal forms. However, a set of all peak positions to those of the affect the energies of external crystal lattice careful examination of the Figure 11 reference spectra of crystal forms that vibrational modes. The spectra in Figure spectra reveals that where correspond- one has already acquired to confirm the 9 very clearly demonstrate the oft heard ing bands appear in both spectra they crystallographic identity of the sample. claim that the low frequency region of all do so at the same peak position to Isn’t the measurement of the Raman the Raman spectrum attributable to ex- within 1 cm-1, thereby confirming that band differences redundant to just ternal crystal lattice vibrational modes is the grains are of the same crystal form. matching the peak positions to refer- the most sensitive to crystal structure and Carbamazepine polymorph difference spectra? Not necessarily, particu- thereby the most effective for differentiat- entiation through Raman spectros- larly if one encounters a spectrum that ing multiple forms of molecular crystals. copy requires the acquisition of spectra doesn’t exactly match any of the refer- Finally, it is important to note how strong with resolution sufficient to detect the ence spectra. If the complete set of peak the Raman scattering is from external small differences in peak positions of positions of a sample spectrum does not crystal lattice vibrational modes. In all but the various crystallographic forms. Pre- match any of those of your reference one of the spectra shown in Figures 4–6, sentation of the carbamazepine forms spectra, you may have discovered a new the signal strengths of the bands below 200 I and III spectra to show only the 1200 polymorph. This is where the measure- cm-1 are comparable to or greater than the to 1750 cm-1 region in Figure 12 reveals ments of the differences in peak posi- most intense Raman bands in the higher small differences in the peak positions tions can help you characterize this new frequency portion of the fingerprint re- just as we had observed for the differ- crystal form. It is likely that the refer- gion. Consequently, analyzing the low ent forms of paracetamol. The general ence crystal form that yields the small- frequency portion of the Raman spectrum patterns of band location and relative est differences in Raman peak positions for characterizing polymorphism is par- intensities are similar. However, all of relative to those of your unknown or ticularly advantageous, because it is both the peak positions of corresponding sample spectrum has a crystal structure sensitive to crystal structure and yields bands of forms I and III differ by vary- very close to that of the newly discov- very strong signals. ing degrees. There are no correspond- ered polymorph. ing bands at the same peak position. Finally, we again review the spectral re- Carbamazepine Forms I and III The smallest difference is between the gion between 10 and 300 cm-1 correspond- Carbamazepine is a pharmaceuti- 1488 and 1490 cm-1 bands of forms I ing to the external crystal lattice vibrations. cal compound and molecular crystal and III, respectively. Therefore, the The low frequency portions of the spectra that can be found in multiple crystal- high frequency portion of the finger- of carbamazepine forms I and III shown in lographic forms. Like paracetamol, print region can be used to differentiate Figure 14 are strikingly different. In fact, it is carbamazepine can be melted or dis- carbamazepine forms I and III. difficult to even recognize any correspond- solved in a suitable solvent to generate Examination of the spectral region ing bands of the two forms below 200 cm-1 individual molecules. Therefore, the between 500 and 1100 cm-1 reveals even though a correspondence is clearly Raman spectrum of solid state car- that most of the corresponding Raman recognizable for all of the bands greater bamazepine consists of bands arising bands of carbamazepine forms I and III than 500 cm-1 throughout the spectral fin- from external and internal crystal lat- have different peak positions that will gerprint region as seen in Figures 12 and tice vibrational modes as seen in the allow a spectrometer with sufficient 13. Once again, we see how significantly spectra of carbamazepine forms I and spectral resolution to resolve them and different the peak positions of bands aris- III shown in Figure 10. The spectra differentiate the crystal forms (See Fig- ing from external crystal lattice vibrations of forms I and III appear similar, but ure 13). It is worth noting here that one are, thereby demonstrating their sensitiv- are not identical as one might expect can and should use the peak positions ity to the unit cell crystal structure and the from different forms of the same com- and magnitudes of the differences of at configurations of the molecules therein. pound. However, just as we saw for the least several bands to differentiate crys- The low frequency portion of the Raman spectra of paracetamol, relative band tal forms. For example, the spectrum spectrum is clearly the most efficacious for strengths are not to be relied upon of carbamazepine form I has peaks at characterizing, differentiating, and screen- for differentiating crystal forms of the 619, 719, 1025, and 1040 cm-1 for which ing polymorphs by Raman spectroscopy. same compound. The spectra shown the corresponding Raman bands in in Figure 11 were obtained from dif- form III appear at 621, 724, 1025, and Conclusion ferent grains of carbamazepine form 1043 cm-1, respectively. Therefore, the Raman spectroscopy is sensitive to crystal III and yet appear significantly differ- magnitudes of the form I minus form structure, and has therefore been success- ent particularly in the region below 200 III band positions of this set are -2, -5, fully used for the characterization and www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 21 screening of crystal polymorphs. Group modes are most sensitive to the configura- Interscience, New York, 1972), pp. 6–19. theory in conjunction with Raman polar- tions of molecules within the unit cell and (5) W.G. Fateley, F.R. Dollish, N.T. McDevitt ization selection rules has been applied to their molecular interactions. The results and F.F. Bentley, Infrared and Raman differentiate the anatase and rutile TiO2 very clearly demonstrate the oft heard claim Selection Rules for Molecular and Lattice crystal structures by their Raman spectra. that the low frequency region of the Raman Vibrations: The Correlation Method (Wi- Nevertheless, the interpretation of even spectrum attributable to external crystal ley-Interscience, New York, 1972), p. 165. simple spectra such as those of anatase and lattice vibrational modes is the most sen- (6) G.A. Tompsett, G.A. Bowmaker, R.P. rutile TiO2 is not straightforward, and we sitive to crystal structure and thereby the Cooney, J.B. Metson, K.A. Rodgers and are aided in our band assignments and most effective for differentiating multiple J.M. Seakins, J. Raman Spectroscop. 26, spectral interpretation by previously pub- forms of molecular crystals. Consequently, 57–62 (1995). lished work. The Raman spectra of mo- analyzing the low frequency region of the lecular crystals were explained in terms Raman spectrum for characterizing poly- of external and internal crystal lattice vi- morphism is particularly advantageous be- David Tuschel is a brational modes occurring in the low and cause it is both sensitive to crystal structure Raman Applications Sci- high frequency regions, respectively. The and yields very strong signals. entist at Horiba Scientific, energies of the crystal lattice vibrational in Piscataway, New Jersey, modes depend upon the configuration of References where he works with Fran the molecules within the crystallographic (1) D. Tuschel, Spectroscopy 29(9), 14–21 Adar. David is sharing authorship of this column unit cell and in particular their molecular (2014). with Fran. He can be interactions. Crystal forms of paracetamol (2) P.M.A. Sherwood, Vibrational Spectros- reached at: Spectroscopy- and carbamazepine were differentiated by copy of Solids (Cambridge University [email protected] their peak positions in both low and high Press, London, 1972), p. 4. frequency regions. Spectral resolution of 1 (3) D. Tuschel, Spectroscopy 30(12), 17–22 cm-1 or better is required for effective poly- (2015). morph differentiation. The low frequency (4) W.G. Fateley, F.R. Dollish, N.T. McDevitt For more information on region is the most efficacious for differenti- and F.F. Bentley, Infrared and Raman Se- this topic, please visit: ating crystal forms. That is because the en- lection Rules for Molecular and Lattice Vi- www.spectroscopyonline.com/adar ergies of external crystal lattice vibrational brations: The Correlation Method (Wiley- We make a great paIR! Hamamatsu IR lasers and detectors

IR detectors ■ InAsSb material that’s RoHS compliant. That means no mercury or lead! ■ Dependable manufacturing consistency ■ Different package options and sensitivity out to 11 microns ■ New optimized detectors for 3-5 micron measurements

IR lasers ■ CW and pulsed QCLs

■ DFB lasers with industry leading linewidth resolution ■ No-mode-hopping guarantee ■ Custom wavelength capability

Get the performance you need

www.hamamatsu.com | 1-800-524-0504 22 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

IR Spectral Interpretation Workshop Organic Nitrogen Compounds II: Primary Amines

In the second installment in our survey of the infrared spectroscopy of organic nitrogen compounds, we look at amines. These molecules contain carbon, hydrogen, and nitrogen. They come in six varieties, and, by using the N-H stretching peak positions by themselves, we can distinguish between all the different amine types. The Infrared Spectral Interpretation Challenge also returns after its holiday hiatus.

Brian C. Smith

any years ago, the American Chemical Soci- goes down. Thus, a primary amine contains two N-H ety issued a series of bumper stickers with bad bonds, a secondary amine contains one N-H bond, and M chemical puns on them. My favorite, given my a tertiary amine contains no N-H bonds. This can be a background, was “Honk if you passed P-Chem.” An- little confusing, but as long as you remember that the other was, “It takes Alkynes to make a world.” But the amine names are counting the number of carbons at- one most relevant to this column was, “It’s Amine Old tached to the amine nitrogen (and not the number of World without Chemists.” It would be a mean world hydrogens), you will be all right. without chemists, or amines for that matter. Amines The nature of the alpha carbons in an amine plays a comprise a part of amino acids, from which proteins role in determining the type of amine. If one or more of are made. It is hard to imagine life on earth without the alpha carbons are saturated in the functional group, these molecules. it is called a saturated amine. If one or more of the The amine functional group contains carbon, hydro- alpha carbons are aromatic, then the moiety is called gen, and nitrogen, and consists of C-H and C-N bonds. an aromatic amine. But what happens when one alpha Amines are divided into three categories, called pri- carbon is saturated and the other is aromatic, as is the mary, secondary, and tertiary amines. Their molecular case for the molecule N-methylaniline seen in Figure 2? structures are seen in Figure 1. The answer is that aromaticity wins. If any of the alpha Note that amines consist of a central nitrogen atom, carbons in an amine are aromatic, the amine is consid- called an amine nitrogen, single-bonded to various ered aromatic. Thus, N-methylaniline is an aromatic numbers of carbons and hydrogens. Any carbon atom amine. Ultimately, then, there are six different kinds of attached directly to the nitrogen is called an “alpha amines: primary saturated, primary aromatic, secondary carbon.” The amine group structural names count the saturated, secondary aromatic, tertiary saturated, and ter- number of carbons attached to the amine nitrogen. tiary aromatic. Note it takes not one but two adjectives Thus, a primary amine contains one C-N bond, a sec- to properly describe an amine. All these types of amines ondary amine contains two C-N bonds, and a tertiary may be bewildering, but, as we will see below and in future amine contains three C-N bonds. Note that as the num- columns, infrared spectroscopy can be used to distinguish ber of C-N bonds goes up, the number of N-H bonds all these different types of amines from each other. www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 23

Figure 1: The molecular structure of primary, secondary, and tertiary amines. Note the locations Figure 2: The chemical structure of of the amine nitrogen and alpha carbon. N-methylaniline, an aromatic amine.

Recall from the last column (1) gens move in opposite directions, stretch, and 3298 cm-1, which is the that organic nitrogen atoms form with one hydrogen moving towards symmetric stretch (going forward, somewhat polar N-H bonds, and the nitrogen while the other moves assume all peak positions are in that these functional groups can away. For the symmetric stretch, cm-1 units). Note that the peaks are form hydrogen bonds. The hydrogen however, both hydrogens move to- somewhat broadened, a couple hun- bonding of amine groups to each gether in the same direction, either dred wavenumbers wide at the base, other is seen in Figure 3. towards or away from the nitrogen. narrower than O-H stretching peaks Because of electronegativity dif- For both methylene, water, and pri- that can be upwards of a thousand ferences, the nitrogen carries a par- mary amine groups, the number of wavenumbers wide. However, these tial negative charge, the hydrogen a spectroscopically useful hydride N-H stretches are broader than the partial positive charge, and they co- stretching vibrations matches the C-H stretches seen in the spectrum ordinate with each other as shown. number of hydrogens attached to the just below 3000. central atom. In all cases, this is two. As seen in Table I, saturated pri- The Infrared Spectroscopy As we will see in the next column, an mary amine asymmetric stretching of Primary Amines easy way to distinguish primary and peaks fall from 3380 to 3350, whereas As we discussed last time (1), it is secondary amines is that primary the saturated symmetric stretching N-H stretching and bending peaks amines contain two N-H bonds, peak appears between 3310 to 3280. that are your best guide to identify- and hence have two N-H stretching Also note in Table I that there are ing the presence of nitrogen in an peaks, whereas secondary amines separate N-H stretching peaks for organic compound. The primary have only one N-H bond, and only saturated and aromatic primary amine-NH2 group has structural one N-H stretching peak. The NH2 amines. For primary aromatic similarity to the methylene or CH2 group has a scissors bending vibra- amines, the asymmetric and sym- group we have studied previously tion where the two hydrogens bend metric N-H stretches fall from 3500 (2), and to water. In all cases, there towards or away from each other, as to 3420, and 3420 to 3340, respec- is a central atom with two hydro- seen in Figure 4. Primary amines tively. Note that the N-H stretching gens attached, and all three atoms also have an out-of-plane bend or peaks of saturated primary and aro- are in the same plane. Of course, in “wagging vibration,” where the two matic primary amines are different the case of the methylene group, the N-H bonds bend together above and from each other, which means these central atom is a carbon; for water, below the plane of the page. peaks can be used to distinguish pri- the central atom is an oxygen, and, The spectrum of a primary mary saturated amines from primary for a primary amine, the central amine, propylamine, is seen in Fig- aromatic amines. The pair of peaks atom is a nitrogen. One difference ure 5. The two N-H stretching peaks labeled A and B in Figure 5 then between these molecules is the bond labeled A and B are the indication carry an unusually large amount angles. In a methylene group, it is that this is a primary amine. of information. The pair of N-H 109 °; in water, they are about 104.5 Recall from last time (1) that N-H stretches means the amine is pri- °, and, in a primary amine, the bond stretches fall in the same wavenum- mary, and the peak positions mean angles are 120 ° (3). ber range as O-H stretches, but the amine is saturated. Primary amines have the stretch- that N-H stretches are easy to dis- The primary amine group also ing and bending vibrations seen in tinguish, because they will be less has a scissoring vibration, as seen Figure 4. Like a methylene group broad and less intense. This is due in Figure 4. Both the water mole- and water, a primary amine has two to N-H bonds being less polar than cule and the methylene group have stretching vibrations, an asymmetric O-H bonds (1). The N-H stretches similar vibrations. According to and symmetric stretch. Note that, for of propylamine fall at 3369 cm-1, Table I, the primary amine scissors the asymmetric stretch, the hydro- which is assigned as the asymmetric peak falls from 1650 to 1580. Note 24 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

Figure 3: An illustration of the hydrogen Figure 4: Vibrations of the primary amine group. bonding that takes place in amines. that this peak position is the same whether the primary amine is saturated or aromatic. We have seen (4) that the water molecule’s scissoring peak falls around 1630. However, the same maxim that applies to NH and OH stretches also applies to their bending vibrations; peaks from O-H bonds will generally be broader and more intense than those from N-H bonds. The propylamine N-H scissors peak at 1606 is labeled C in Figure 5. It shows up near where the water scissors peak appears, it is somewhat broadened, but is not wide enough to be mis- taken for an OH bending peak. The last useful group wavenumber for primary amines is the NH2 wagging peak. It falls from 850- 750, as seen in Table I, and has the same range for both saturated and aromatic primary amines. In the spectrum of propylamine in Figure 5, it is found at 812 and is labeled E. Note that it is somewhat broadened like the primary amine N-H stretch- Figure 5: The infrared spectrum of propylamine (wavenumber positions shown within table). ing and scissoring peaks, again due to hydrogen bonding. A primary amine does contain a with only a few peaks in its finger- to two, to three, the number of C-N bond, and, yes, there will be print region. For any molecule larger N-H bonds goes from two, to one, a C-N stretching peak as a result. or more complex, this C-N stretching to zero. The nature of the carbons However, as we discussed last time peak would be lost in the shuffle. attached to the nitrogen also deter- (1), because C-N stretches are not mines whether the amine is satu- that polar, their peak intensities are Conclusions rated or aromatic. There are six not strong, and they have the mis- Amines are a class of nitrogen con- types of amines: primary saturated, fortune of falling in the busy fin- taining organic compounds that primary aromatic, secondary satu- gerprint region (1600 to 1000 cm-1) consist of C-H and C-N bonds. rated, secondary aromatic, tertiary of the mid-infrared spectrum. The There are three types of amine: saturated, and tertiary aromatic.

C-N stretch of propylamine is at primary, secondary, and tertiary, Primary amines contain an NH2 1072, and is labeled D in Figure 5. which are determined by the num- group, and their spectra are domi- Note how small and nondescript this ber of C-N bonds in the functional nated by the stretching and bending peak is. It can be seen here because group. As the number of C-N bonds of this moiety. Primary amines are propylamine is a simple molecule, in an amine group goes from one, distinguished from secondary amines www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 25

Quiz Section Your Next Infrared Spectral Interpretation Challenge Using everything you have learned in this and previous columns, determine the functional groups present, and try to discover the chemical structure of this compound as shown in Figure i. Remember that inclusion of a peak position in the table does not necessarily mean that it will be useful in the structural determination.

Figure i: The infrared spectrum of a liquid. Sampling technique: thin film.

Table I: The infrared group wavenumber (4) Brian C. Smith, Spectroscopy, 31(1), regions for primary amines (in cm-1) 14–21 (2016). Vibration Saturated Aromatic NH Asymmetric 2 3380-3350 3500-3420 BrianB C. Smith, stretch PPhD, is founder and NH Symmetric CEOC of Big Sur Scientific, 2 3310-3280 3420-3340 stretch a maker of portable mid-infraredm cannabis NH2 Scissors 1650-1580 1650-1580 analyzers.a He has over C-N Stretch 1250-1020 1350-1250 303 years experience as NH Out-of- ana industrial infrared 2 850-750 850-750 plane bend spectroscopist, has published numerous peer reviewed papers, and has written 3 by the presence of two N-H stretch- books on spectroscopy. As a trainer, he ing peaks instead of one. The po- has helped thousands of people around sitions of these two peaks disclose the world improve their infrared analyses. whether the primary amine is satu- In addition to writing for Spectroscopy, rated or aromatic. There are also Dr. Smith writes a regular column for its two NH2 bending vibrations for pri- sister publication Cannabis Science and mary amines that can be useful for Technology and sits on its editorial board. identifying this functional group. He earned his PhD in physical chemistry from Dartmouth College. He can be References reached at: [email protected] (1) Brian C. Smith, Spectroscopy, 34(1), 10–15 (2019). (2) Brian C. Smith, Spectroscopy, 30(4), 18–23 (2015). For more information on this topic, (3) A. Streitweiser and C. Heathcock, please visit our homepage at: Introduction to Organic Chemistry www.spectroscopyonline.com (Macmillan, New York, 1976). 26 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

2019 Salary Survey: Some Unusual Trends

The 2019 Spectroscopy salary and employment survey extracted from calendar year 2018 trends shows a marked decrease in salaries from previous survey years. At the same time, nearly two-thirds of respondents said they were either highly satisfied or satisfied with their current positions.

Jerome Workman, Jr.

his year’s Spectroscopy salary survey results showed for the gender gap in salaries, there is a clear and significant a 14% decrease in average base salaries reported, as difference between male and female salaries. However un- T compared to 2018 survey numbers. A comparison of less the age effect and other effects are accounted for, such the survey sampling population from 2018 to 2019 indicated as education and years of experience, the raw differences are a slight decrease in the average age of respondents this year, difficult to interpret precisely. That being said, the salaries with more respondents from the Midwest (USA), and fewer for full-time male workers this past year averaged $84,602, from industry (54.6% versus 67.9%); these factors would be compared to $67,235 for full-time female workers. This is expected to reduce the average salary values somewhat. Last a negative gap of 25.9%, which is statistically meaningful. year, 38.3% reported their job titles as laboratory director or manager, whereas this year only 17.2% reported similar job TABLE I: Average reported base salaries from 2001 to 2019 titles; this significantly reduced the number of $125,000-plus salaries within the survey data (see the box insert within this Percent change vs Survey year Average salary (USD) previous year article to learn how the survey was conducted). The salary trends over the history of this survey from 2001 to present 2001 $64,690 (first year) NA are shown in Table I and Figure 1. Given that these results 2002 $67,900 5.0% and our corresponding analysis were so surprising, we calcu- 2003 $68,180 0.4% lated the results multiple times; each calculation yielded the 2004 $72,140 5.8% same results. The high number of survey responses this year 2005 $72,920 1.1% (n = 405) provided a good sample population for salary calcu- 2006 $77,980 6.9% lations; possibly the salaries will once again trend upward in future years. For the statisticians out there, the median and 2007 $79,605 2.1% mean values were not widely different, suggesting a somewhat 2008 $77,364 –2.8% normal distribution of salary values. One might also observe 2009 $78,807 1.9% from the past five years (1–5) that last year’s reported salary 2010 $80,778 2.5% increases may be somewhat of an anomaly as well (Table I and 2011 $84,511 4.6% Figure 1). Subsequent years may reveal additional cause(s) for 2012 $85,060 0.6% such dramatic changes. 2013 $88,018 3.5% Salary Trends and Data 2014 $88,342 0.4% Average Salaries by Gender, Sector, Education, and Age 2015 $83,209 –5.8% As shown in Table II, the average male base salary of $84,602 2016 $82,457 –0.9% is comparable to the 2015 survey average, and the lowest re- 2017 $84,718 2.7% corded over the past five years. Female salaries followed a 2018 $91,129 7.6% similar trend, with an average value of $67,235, also repre- senting the lowest survey results over the past six years. As 2019 $79,711 –14.3% www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 27

When comparing sector data, average have declined for all age groups com- FIGURE 1: Trend line of average reported base salaries survey base salaries decreased in aca- pared to last year’s survey. The 60+ from 2001 to 2019. demia to an average of $58,250, a large year age group had an average salary of downward trend of $15,231. For the in- $83,212, down from $97,816 last year; dustrial sector, the average salary was this was a –17.6% change. The 50–60 $86,800, a decrease of $11,662 over last age group had the most dramatic change, year. Reported government salaries were dropping 27.7%, from $106,573 last year also lower, with an average of $77,111, a to $83,488 this year. The 40–50 age decrease of $3,252 over the 2018 survey. group averaged $82,725 this year, down Breaking the average salaries down 2.8% from last year’s value of $85,004. by education level reveals a startling re- The under 40 age group averaged duction of 23% from last year for those $62,365 this year versus $70,589 in the who have completed a PhD. The current 2018 survey, a change of –13.2%. average of $94,939 is roughly equivalent to that of 2015. This year’s data also in- Average Regional Salary

Survey year dicated that our sampling population Differences in the United States with bachelor’s degrees had higher av- Table III and Figure 2 show average base erage salaries than those at the master’s salaries for full-time workers in differ- degree level. This ranking of salaries ent geographical regions in the conti- was also observed in the 2014 and 2016 nental United States. The Southwest surveys. Master’s level salary reductions and Southeast had a marked increase in from 2018 to 2019 were 23%. The bach- average salaries compared to last year. elor’s level salary decrease from last year The Southwest had the largest uptick, to this year was much less exhibiting a from $84,132 to $94,049,, an increase 0.5% decrease, indicating some solidity of 11.8%. Salaries in the Southeast grew Average base salary (usd) in bachelor’s level career positions. 4.3%, from $84,000 to $87,622. Other Survey data indicated that salaries sectors had decreases in average sala-

EXTENDING RAMAN Into the THz Domain

2XUSDWHQWHGbTHz-Raman® Spectroscopy SystemsbFRPELQHFKHPLFDO GHWHFWLRQDQGVWUXFWXUDODQDO\VLVLQDVLQJOHLQVWUXPHQW%\LPSURYLQJERWK SURFHVVDQGVFLHQWLFDQDO\VLVWKLVFRVWHHFWLYHWHFKQRORJ\GHOLYHUVIDVWHU DQGPRUHUHOLDEOHUHVXOWV&RKHUHQWQRZRHUVDIXOOOLQHRI7+]5DPDQ® SURGXFWVDQGKLJKSHUIRUPDQFHODVHUVIRU\RXUPRVWFKDOOHQJLQJSURFHVV RUUHVHDUFKVSHFWURVFRS\DSSOLFDWLRQV

ONDAX is now Coherent, Inc. Learn More—ZZZ7+]5DPDQFRP 28 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com ries, with the most dramatic drop in the For males working in industry, the reported see that salary gaps between male and fe- Northeast, at –20%, a drop from $92,381 average salaries dropped from $108,068 male worker’s salaries for all groups are sig- to $73,822. This is followed by a decrease last year to $94,765 this year, a –14.0% drop. nificant, and remain that way. Even though in the Northeast of –14.0%, with aver- For females working within the industrial there have been variations from year to year, age salaries dipping from $107,313 to sector, salaries dropped from last year’s the problem seems to be changing very little, $92,295. Midwest salaries decreased $85,161 to this year’s $71,621, a –18.9% dip. according to our survey data. 6.5%, from $88,940 to $83,172. Overall, In academia, average salary changes from the Southwest exhibited the highest sala- last year to this year were $78,946 to $61,263 Bonuses, and Salary Increases ries followed by the Northeast, then the for males, and $69,231 to $54,778 for fe- The average annual base salary for Southeast, Midwest, and Northwest. males. In government work, average salary 2018 (2019 survey) for full-time work- changes from last year to this year were ers was $79,711. Fewer than half of our A Closer Review of the Gender Gap $81,247 to $80,042 for males, and $76,800 respondents (46.42%) received a bonus, When we look at the ongoing gender pay to $69,200 for females. whereas 53.6% did not. For those who gap (Table IV), we first note that all groups, If we are to compare salary gaps over did receive bonuses, the average bonus irrespective of gender, reported a down- the past five years in dollars (Table II) and was $12,026 for U.S. full time workers trend in salaries for this year versus last year. percentage (Figure 3) for all categories, we and $11,962 for all full-time workers (U.S. plus international). TABLE II: Average salaries by gender, sector, education, and age Salary increases by percentage for this past year are shown in Table V. 2014 2015 2016 2017 2018 2019 From the table we can see that 17.22% All Respondents $88,342 $83,209 $82,457 $84,718 $91,129 $79,711 did not expect any increase, but 27.41% Gender faced this reality; fully more than 10% Male $93,664 $85,898 $87,118 $90,781 $100,353 $84,602 of respondents that expected a raise did not receive one. From the table, one can Female $71,601 $75,813 $73,728 $73,653 $79,770 $67,235 see that 16.01% (8.46% + 2.11% + 5.44%) Sector expected an increase of 5% or more, and Academia $72,389 $74,447 $67,208 $67,106 $73,481 $58,250 15.66% (6.02% + 4.22% + 5.42%) actu- Industry $94,049 $85,886 $89,488 $91,931 $98,462 $86,800 ally received this level of raise. Nearly Government $84,596 $82,084 $77,720 $80,341 $80,363 $77,111 84% (17.22% + 37.46% + 29.31%) of re- Education Level spondents expected to receive less than a 4% increase, and, lo and behold, 84% Bachelor’s $79,458 $71,022 $68,167 $67,361 $76,325 $75,982 degree (27.41% + 34.64% + 22.29%) actually did receive a salary increase of 4% or Master’s degree $73,628 $80,685 $67,373 $70,720 $82,402 $67,081 less during the survey year–remark- PhD $104,036 $96,716 $101,717 $128,380 $116,475 $94,939 able! We can see from the table that, Age (Years) even though expectations for salary in- <40 $65,594 $66,357 $61,958 $65,849 $70,589 $62,365 creases among respondents is not overly 40–50 $83,808 $81,069 $88,621 $83,237 $85,004 $82,725 optimistic, even these low expectations 50–60 $95,663 $93,454 $88,026 $103,336 $106,573 $83,488 were not met. From column 4, we can observe that over 20% (the sum of col- 60+ $102,924 $101,925 $89,227 $104,409 $97,816 $83,212

TABLE III: United States regional breakdown of employment sector and average salary

Northwest Southwest Midwest Northeast Southeast Sector breakdown for each region (percentage in each group) Academia $50,000 $69,500 $65,420 $63,909 $50,250 Industry $74,136 $103,752 $91,747 $102,428 $104,657 Government $68,480 $83,125 $77,193 $87,800 $80,683 Average salary by region 2017 $85,750 $90,569 $80,195 $84,338 $98,720 2018 $92,381 $84,132 $88,940 $107,313 $84,000 2019 $73,822 $94,049 $83,172 $92,295 $87,622 Change (2019 versus 2018) –20% 11.8% _–6.5% –14.0% 4.3% Northwest (OR, WA, ID, MT, WY, AK); Southwest (CA, HI, AZ, NM, NV, CO, UT, OK, TX); Midwest (OH, IN, IL, IA, MO, MI, MN, WI, KS, ND, SD, NE); Northeast (MA, CT, NY, NJ, PA, VT, NH, RI, ME); Southeast (LA, MS, AL, GA, FL, TN, KY, NC, SC, AR, DE, VA, WV, MD, DC) www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 29 umn 4, Table V) did not have their salary competitive with salaries for similar same, and 4.6% reported a decrease in increase expectations met. positions in other organizations, 54% workload. Last year, 63.5% stated their For most respondents (63%), salary disagreed. When asked the ultimate workload had increased over previous increases were perceived to be based on question if one would consider leaving years. The perceived reasons for in- organizational success, whereas 31% be- a science career to make more money, creased workload during this past year lieve their salary increases were based only 39.3% said they would. are shown as Figure 5. Increased busi- on personal achievements (Figure 4). ness and added responsibility for an When asked if salary increases fairly Workload and existing position were the main causes reflected personal performance, 64% Paid Time Off During 2018 for workload increases. New equip- did not agree, and when asked if their Workload ment, staffing cuts, and new regula- annual salary increase keeps up with During this past year, 56.0% of respon- tions comprised the next set of factors. inflation, 70% said it did not. When dents reported an increased workload, From Table VI, we see that, although asked if compensation received was 38.8% said their workload stayed the only 26.78% (22.68% + 4.10%) of re-

FIGURE 2: The average base salaries by U.S. region for the FIGURE 3: Salary gap between male and female workers over 2019 survey from low to high. past six years (as percentage average salary difference). Male versus female salary gap Average base salary (usd) Average

Region (usa)

TABLE IV: Male versus female average salary, 2016–2019

2016 2017 2018 2019 Male Female Male Female Male Female Male Female Employer type Industry $93,120 $82,193 $101,811 $76,347 $108,068 $85,161 $94,765 $71,621 Academia $74,153 $55,633 $65,770 $58,337 $78,946 $69,231 $61,263 $54,478 Government $81,149 $66,289 $83,140 $74,510 $81,247 $76,800 $80,042 $69,200 Management versus nonmanagement Management $97,727 $84,870 $104,190 $83,625 $112,058 $91,065 $93,935 $67,098 Nonmanagement $74,299 $66,300 $82,193 $69,121 $80,546 $71,913 $74,818 $67,354 Education level Bachelor’s $72,411 $63,014 $66,473 $68,507 $84,648 $64,781 $81,114 $67,609 degree Master’s degree $70,134 $61,211 $68,986 $62,835 $92,106 $71,312 $71,563 $58,782 PhD $103,051 $98,236 $133,287 $110,716 $125,391 $104,473 $99,608 $79,429 30 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

of paid vacation, while 26.23% receive TABLE V: Respondents showing actual versus expected salary increases for 2018 two weeks or fewer of paid time off. We Percentage of Percentage of Difference should consider that 39.25% of respon- respondents respondents who (percentage of dents have been with the same organiza- who expected a actually received respondents 2018 Salary salary increase a salary increase who got less tion for 10 or more years; 18.0% of the increase vs. 2017 in this range in this range than expected) entire surveyed group has remained 0% 17.22% 27.41% 10.19% with the same organization for more 1–2% 37.46% 34.64% 2.82% than 20 years. Happily, more than half (51.1%) of respondents have four or more 3–4% 29.31% 22.29% 7.02% weeks of vacation. 5–6% 8.46% 6.02% 2.44% 7–8% 2.11% 4.22% –2.11% Job Satisfaction Intangibles 9% or greater 5.44% 5.42% 0.02% Career Fulfillment Factors For this 2019 survey, 65% of respondents spondents are contracted to work more said they were either highly satisfied or FIGURE 4: Breakdown of than 40 or hours per week, 58.47% ac- satisfied with their current position, perceived basis (personal, team, or organizational success) for salary tually worked more than 40 hours per whereas 35% were either highly dissat- increases. week, and almost 15% admitted to isfied or somewhat dissatisfied. In an- working more than 50 hours per week other form of this question, 60% of re- on average. These work numbers are as spondents said their job met their career expected for professionals. expectations, while 40% said it did not. The survey asked a number of detailed Paid Time Off (Vacation) questions related to career fulfillment, Allotted paid vacation for respondents and these responses are given in Table during 2018 is shown in Table VII. We VIII. A full 76% felt that their work was see from the table that 28.15% or re- valued by their employer, and 83% felt spondents are given five weeks or more their job was secure. A remarkable 75.7% responded that they use their skills and training to its fullest extent in their cur- FIGURE 5: Percent of respondents indicating various perceived causes for their increased workload. rent position. Overall, the career fulfillment responses were extremely positive!

Bullying in the Workplace Last year’s survey dealt heavily with sexual harassment in the workplace. This year, the editors decided to look more closely at another issue that re- ceives far less attention, but that can also cause serious work stress without much opportunity for workers to get relief: bullying. We asked a number of related questions with some surprising results (Table IX). Just under half (47.7%) of respondents feel unable to express their concerns at work. The same percentage of respondents feel that they do not have sufficient authority to accomplish their jobs. A total of 23% feel bullied or intimidated at work, with 10.8% admitting they have been publicly humiliated by their boss. Note Other Stafﬁng cuts that work stress levels in 2018 were per- New equipmentNew regulations Increased business ceived to have increased for 48.0% of respondents; 45.2 % said that work stress Added responsibility for existingGoing positionthrough a merger or acquisition remained unchanged, with only 6.7% Took a job at a new company or organization Changed positions within the company or organization stating that they had a decrease in work related stress during 2018. www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 31

TABLE VI: Percentage of respondents showing the number of contracted hours expected per week versus actual hours worked

Percentage of respondents Percentage of respondents who Weekly hours contracted to work this amount actually worked this much Discrepancy Fewer than 40 13.11% 9.29% –3.82% Approximately 40 60.11% 32.24% –27.87% 40–50 hours 22.68% 43.72% 20.74% More than 50 4.10% 14.75% 10.65%

Job Choice and Satisfaction respective locations; 50% said it was good candidates to fill these skilled We also asked our respondents about the moderate, and 27% said that the com- roles). A series of questions was asked factors they consider most important petition was weak (which suggests that about the difficulty in finding a satis- to them when evaluating a job (Table employers would have to compete for factory position if one had to change X). The top-ranked factors were salary and bonus structure, work–life balance, and “the team I work with.” Other factors, including job security, intellectual challenge, and a tolerant work place, also rated above 85%. The three least important factors were prestige of the organization, the ability to work from home, and maternity or paternity leave (although we noted that 67.9% of our re- Savillex spondents are age 40 or over). C-Flow Nebulizers

Other Benefits and Consistent nebulizer-to-nebulizer performance. Job Fulfillment Issues Guaranteed. The survey also asked about other work benefits, such as sponsored technical conference attendance, payment of professional dues, provision for participa- C200 tion in inventions and patent work, and recognition of achievement by management. From Table XI, one can see that only 5.16% are permitted to attend five or more conferences, while 66.06% may C700d attend none or just one sponsored con- C400e ference per year. When asked if their organization pays their professional dues, only 35.5% answered yes. When asked if the organization allows workers to participate in inventions or patents, just under half (49.4%) said they did. When Don’t Settle for Less. asked if individuals or teams received special recognition from management With over 35 years experience in ﬂuoropolymer molding, during 2018, only 28.7% said they had, Savillex brings unmatched expertise and know-how to ICP sample introduction design. All of our products are with a large majority of 71.34% telling designed and manufactured in-house, using only the us they had not. highest purity grade PFA resins.

For more information The Job Market and Job visit www.savillex.com/ICP Prospects How Easy is it to Find a New Position? The job market for spectroscopy related positions was also considered in Savillex Corporation this survey. From a series of questions, 10321 West 70th St. | Eden Prairie, MN USA | Phone: 952.935.4100 23% of respondents said competition was strong for such positions in their 32 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com jobs. 12.3% said it would be straight- To Be or Not to Be management. Of those that have had forward to find an equivalent position; (in Management)? formal business or management train- 40.2% said it would take some time, but Formal Academic ing, a series of questions was asked to it would be possible to find a compara- Management Training determine the perceived value in taking ble position; 21.7% said they could find Just over half (51.3%) of our respondents additional time and expense to complete another job, but it probably wouldn’t be have a recognized management role at formal academic training in addition to as good as their current position; and work, with 63.9% of those having 1–5 their scientific or engineering training. 25.8% said a search would be diffi- direct reports, and 5.4% of managers The responses are given in Table XII. cult, and they would take whatever job having greater than 30 direct reports Those formally trained in business man- they could find. Thus, just under half (Figure 6). For the total respondent agement are in strong agreement that (47.5%) of respondents present a poor population, just 20% said they had for- this training has given them a marked outlook for job opportunities. mal academic credentials in business or advantage in the workplace, that the time and money invested was worth it, TABLE VII: Entitlement for paid vacation in 2018 and that this training has led to greater job responsibility. One might note here Paid vacation entitlement Portion of respondents that, historically, the base salaries for 1 week or less 8.47% managers have averaged much higher 2 weeks 17.76% than for nonmanagers. 3 weeks 22.68% 4 weeks 22.95% Salary Advantages in Management 5–6 weeks 21.86% In 2019, there was little base salary difference reported between management and 7–8 weeks 3.28% nonmanagement positions for women More than 8 weeks 3.01% ($67,098 versus $67,354, respectively).

TABLE VIII: Career fulfillment factors showing detailed responses

Career fulfillment factor Agree Disagree My work is fully valued by my employer. 75.99% 24.01% My job is secure. 82.34% 17.67% In my current position, I use my skills and training to their fullest extent. 75.71% 24.30% There is opportunity for career advancement in my current position. 49.72% 50.29% There are opportunities to engage in professional development at my current company. 65.16% 34.84% My gender is not a factor in determining or limiting my 85.83% 14.17% professional advancement at my current company. I experience no discrimination for any reason at my current company. 79.66% 20.33% I would not leave my job, given the opportunity. 54.24% 45.76% I would not like to change careers and leave. 66.28% 33.71%

TABLE IX: Responses related to workplace bullying (in rank order)

Issues related to workplace bullying Agree Disagree I am not able to express my concerns freely at work. 47.69% 52.31% I do not have sufficient authority to accomplish my job. 47.69% 52.31% My boss is more often overly critical. 29.69% 70.32% My boss expects me to check with him or her for even minor issues. 29.23% 70.77% My boss does not respect me. 27.70% 72.31% My boss takes control of most conversations. 27.69% 72.31% I feel defenseless with the management at my work. 27.69% 72.31% I am often bullied or intimidated at work. 23.08% 76.92% My boss demands unreasonable work production. 21.54% 78.46% My boss talks behind my back in a critical way. 21.53% 78.47% My boss abuses his or her power. 20.00% 80.00% My boss has humiliated me in a public setting. 10.77% 89.23% www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 33

an advanced technical degree, and even TABLE X: Factors important for choosing a job (more important or less important and ranked by importance) formal management or business training. The distinction between bachelor’s Factors most important in a job More important Less important and master’s degrees is not so clear, but Salary and bonus structure 94.72% 5.28% obtaining a PhD has yielded significant Work and life balance 93.20% 6.81% salary benefits, according to the data we The team I work with 92.35% 7.65% have seen over the 19 years of this survey. Job security 91.18% 8.83% The Northeast and Southeast regions of the United States traditionally yield the Intellectual challenge 89.41% 10.58% highest salaries, and, as in other pro- Tolerant work place 86.98% 13.02% fessions, years of experience generally Retirement benefits 84.91% 15.09% provide proportional increases in wages. Health insurance 84.71% 15.30% Fewer than half of respondents received The importance of my work 84.41% 15.58% bonuses, and these averaged nearly Quality of equipment and laboratory space 83.09% 16.92% $12,000. Salary gaps by gender are significant, and remain that way. Even though Geographic location 80.96% 19.05% there have been variations from year to Commuting time 80.88% 19.12% year, the gender gap seems to be changing Scientific opportunities 78.53% 21.47% very little, according to our survey data Vacation allotment 77.35% 22.65% over the years. Continued training and education 76.25% 23.75% The survey indicated that over one- Professional advancement 76.24% 23.75% fourth of respondents received no increase in pay last year, and only one in Flexible working hours 74.12% 25.88% seven received a raise of 5% or more. Prestige of my organization 51.02% 48.97% More than 80% received a salary in- The ability to work from home 47.49% 52.51% crease of 4% or less. Most respondents Maternity or paternity leave 30.66% 69.35% believe that salary increases were based on organizational success, that salary increases did not fairly reflect personal TABLE XI: Number of technical conferences respondents were allowed to attend in 2018 performance, and that increases did not keep up with inflation. Well over half of Percentage of respondents those surveyed said their workload had Number of technical conferences allowed to attend this number increased, with respondents reporting 0 –1 66.06% that increased business within their or- 2–4 28.79% ganizations or added responsibility for an 5–7 3.64% existing position were the main causes for 7–9 0.91% this increase. Well over half of the survey >9 0.61% respondents work more than 40 hours per week, with one in seven working agement versus nonmanagement, irre- more than 50 hours per week on average. FIGURE 6: The percentage of managers spective of gender or location, are $91,821 Over half of respondents receive four or with a specified number of direct and $73,318, respectively. This trend rep- more weeks of vacation, while one-fourth reports. resents a 27.5% base salary advantage for receive two weeks or less. those in management positions, though In spite of all this, two-thirds of re- in this year’s data, women did not benefit spondents said they were either highly in this regard. satisfied or satisfied with their current positions, 60% of respondents said their Summary and Conclusion job met their career expectations, and a The 2019 Spectroscopy salary survey full three-fourths felt that their work was results showed a 14% decrease in aver- valued by their employer. Over 80% of age base salaries compared to 2018. Of those that completed the survey felt their course, the demographics of the survey job was secure. Yet one in four expressed have a major effect on results and we feelings of being bullied or intimidated However, there was a significant differ- noted specific differences in this year’s at work, with one in ten admitting to ence for men ($93,935 versus $74,818) respondent pool. Even though there was having been publicly humiliated by a (see Table IV). We note that, over the past a decrease in salaries this year, there is boss. Nearly half of respondents stated four years, the average salaries for man- still financial advantage for acquiring there was an increase in work stress dur- 34 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

ing this past year. Salary and bonus TABLE XII: Perceived benefits of formal academic business or management training (in rank order) structure, work and life balance, and “the team I work with,” were clearly Perceived benefits of formal business or management training Agree Disagree the most important factors to job My training has given me a marked 95.32% 4.69% satisfaction. advantage in the workplace. Two-thirds of responders are al- I believe the time and money invested was worth it. 82.54% 17.46% lowed to attend one (or none) con- My training has led to greater responsibility at work. 80.95% 19.05% ferences per year; just one third have I have greater job satisfaction since completing my training. 72.58% 27.42% their professional dues paid, and just My training has caused an increase in my salary. 70.31% 29.69% under half participate in invention or patent work. Only one in four was My business or management training was worth 69.36% 30.64% more to me than additional technical training. formally recognized for their work I have more authority at work. 68.25% 31.74% performance by their organizations last year. Just one in eight feel I relate better to my senior management since my training. 64.51% 35.48% it would be straightforward to find My job is more secure due to my training. 60.94% 39.07% another equivalent position; one in I have been given more people to directly 60.32% 39.68% four said a search for a new position manage due to my training. would be difficult, and they would I have greater opportunity for promotion since my training. 57.14% 42.86% take whatever job they could find. I have moved away from technical work and 53.96% 46.04% Over half of our respondents have more into management since my training. a formal management role in their current job function, with nearly HOW THE SURVEY WAS CONDUCTED two- thirds of those having 1–5 direct reports and 5% of managers hav- The survey was sent to subscribers on 11/28, 12/4, and 12/10 of 2019. A total of 405 ing more than 30 direct reports. We respondents participated (because respondents could skip questions, the number note that one in five of all respon- of responses collected for each question varied). A broad profile of respondents dents have formal academic creden- appears below. Note the salary data represented only full-time employees making a salary greater than $15,000 per year. tials in business or management. Over the past four years, there has Age range: 2.42% Organic chemicals been an average base salary advan- 7.9% 20–29 years old 10.91% Pharmaceuticals tage of 27.5% for management versus 24.2% 30–39 years old 2.42% Plastics, polymers, or rubber nonmanagement positions, irrespec- 19.1% 40–49 years old 4.55% Physics or engineering tive of gender or location. 27.3% 50–59 years old 8.18% Other area of employment: 21.5% 60–65+ years old 54.6% Industry References Gender: 20.4% Academia – 33.3% female and 66.7% male 12.9% Government or nationally (1) B. Degg, Spectroscopy 29(3), 34 40 funded laboratory (2014). Employment status: 12.1% Other – 86.7% are full-time employees (2) B Degg, Spectroscopy 30(3), 44 49 3.9% are consultants Education level: (2015). 34.0% Doctoral degree 1.2% work part-time as employees (3) L. Botcherby, Spectroscopy 31(3), 3.2% are postdoctoral researchers 27.6% Master’s degree 38–42 (2016). or graduate students 34.2% Bachelor’s degree 2.5% work full-time as contractors 4.2% Associate’s degree (4) L. Botcherby, Spectroscopy 32(3), 0.3% work part-time as contractors Geographical Location: 34–40 (2017). 1.0% are currently not employed 16.0% Southwest (5) L. Botcherby, Spectroscopy 33(3), 1.2% are other 4.6% Northwest 24–33 (2018). Primary field of analysis: 14.2% Southeast 3.03% Agriculture or food 16.7% Northeast is the Senior 42.42% Analytical chemistry 22.7% Midwest Jerome Workman, Jr. 25.8% Outside the United States 5.45% Biotechnology Technical Editor for Spectroscopy and (34 other countries) 0.30% Ceramics LCGC North America. Direct correspon- 1.52% Electronics or semiconductors Years Working in Spectroscopy: dence to: [email protected] ◾ 0.91% Energy or petroleum 18.5% < 5 years 6.06% Environmental 14.2% 5–9 years 1.82% Forensics or narcotics 17.2% 10–15 years 1.82% Inorganic chemicals 14.8% 16–20 years 2.73% Instrument design 26.1% 21–35 years For more information on this topic, or development 6.5% 36–40 years 5.15% Medical biology 2.7% 41+ years please visit our homepage at: 0.30% Metallurgy www.spectroscopyonline.com PRESSING MATTERS Portable Hydraulic Press At PIKE Technologies, we understand the art of KBr pellet making and its importance to Make high-quality KBr pellets with the turn FTIR sampling. High-quality pellets equate of a knob using the PIKE Pixie portable to spectral reproducibility and success with hydraulic press. Simply load your powdered difficult or limited-mass samples. KBr/sample matrix into the die chamber then set the assembled die onto the platform of the press. Force up to 2.5 tons may be applied. Place the die collar containing the newly formed pellet into a holder and position it in the spectrometer’s 2 x 3” slide mount holder for measurement. Pixie’s small footprint makes it easy to store and is ideal for limited bench space environments and glove boxes.

We offer a full line of transmission sampling tools and accessories that produce superior spectra and. make sampling easier, including: . Hydraulic Presses . Evacuable Pellet Press . Manual, Economy Presses . Heavy-Duty Sample Grinders IR Pellet Perfection . Mortars and Pestles KBr Chunks and Powder and More! PIKE Technologies introduces PressPRO, a microprocessor controlled automated hydraulic press designed to produce FIND ALL THE SAMPLE PREPARATION TOOLS consistently superior KBr pellets and enhance YOU NEED AT www.piketech.com the uniformity and quality of transmission samples. PressPRO is capable of a variable force from 1 to 15 US tons. Up to four pressure hold times and ramps may be programmed and performed within a run, and five profiles may be stored on the device. 36 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

Trends in Spectroscopy: A Snapshot of Notable Advances and Applications

From the global climate, to national security, to individual healthcare, spectroscopic measurement factors into every facet of modern life. As always, spectroscopy and spectroscopists are providing the objective observations and measurements that help society make sense of a changing world. This article surveys noteworthy recent advances in and applications of atomic and molecular spectroscopy, touching on their uses in fields such as biomedicine, materials science, environmental monitoring, agriculture, pharmaceutical research, public safety, and more.

Michael MacRae

s it has for generations, spectroscopy remains information. Specific commercial products indicative of a critical tool for answering the questions most broad trends in commercial instrumentation are men- A relevant to society’s health, prosperity, and qual- tioned in a few places, but a more expansive review of ity of life. The core techniques under the spectroscopy new products will appear in Spectroscopy’s post-Pittcon umbrella are well established, but in a state of continual review coming up in the May issue. refinement and adaptation to meet changing demands. Although the appearance of a new blockbuster technique Spectroscopy in Context is a rarity these days, ongoing advances in optics, detec- Whether mapping planet-wide climate shifts, detecting tion, and computing technology drive steady evolution- threats to food and water supplies, characterizing new ary progress in instrument performance, ease of use, and nanomaterials, monitoring personal health indicators, applicability to emerging analytical challenges. or discovering a fundamental natural phenomenon, a To chronicle the evolution of the field, Spectroscopy spectrometer is never far from the action when it comes has for many years published an annual overview of key to society’s emerging inflection points. Therefore, any trends in instrumentation and applications. As the latest survey of recent advances and trends in the field of spec- installment in this series, this article attempts to identify troscopy must be presented in the context of the times. current and emerging trends in the most widely used During the preparation of this article, the federal gov- spectroscopic techniques among Spectroscopy’s reader- ernment was just returning to work (at least for the time ship. It focuses on general trends in the scientific com- being) after the longest partial shutdown in its history. munity as a whole, and the spectroscopy community in Regardless of its ultimate duration, this shutdown (like particular, before presenting separate sections dedicated the 20 previous ones since 1976) will have will have both to atomic and molecular techniques. This article is in no short- and long-term impacts on science and, by exten- way a comprehensive review, but rather an individual sion, spectroscopy. Most employees at science-focused take on the field based on a variety of sources, including federal agencies such as the U.S. Environmental Pro- proceedings of key spectroscopy-focused conferences, tection Agency, the National Oceanic and Atmospheric trend-focused articles in primary research journals, Administration, and NASA had been furloughed, and science articles in mainstream news media, individual the National Science Foundation (NSF) had prepared to researcher and institutional websites, and government cancel dozens of grant proposal review meetings sched- www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 37 uled for January, according to the New York Times (1). converting more complex laboratory techniques, such Consequently, laboratories that depend on federal grant as Raman and nuclear magnetic resonance (NMR), into dollars from affected agencies were preparing to defer field-hardened analyzers. Another twist on the estab- spending for equipment, new graduate students, and lished benchtop spectrometer paradigm is the marriage other research-related expenditures. The shutdown of two or more different techniques into one instrument also cut into attendance at key scientific meetings, to reduce the time, expense, and complexity of obtaining disrupted collection of data for long-term studies, and a multimodal measurement. For example, instruments halted planning for future studies. integrating UV/Vis absorbance with fluorescence and Overall, federal funding for research at academic and mid-IR with far-IR/terahertz measurements have been non-profit institutions has been declining since its peak recognized as some of the most innovative introduc- in 2010–11, but has lately been holding relatively steady tions at recent Pittcons (5). The coupling of vibrational year-to-year, according to a report by the NSF (2). Fed- spectroscopy with various forms of imaging is bringing eral research grants have traditionally been the primary spectroscopy into the nanoscale range. funding source for science at U.S. universities. How- ever, that began to change in 2014, when federal support Trends in Atomic Spectroscopy dropped below 50% of academia’s total research funding Atomic spectroscopy remains a workhorse of the analytical pie for the first time in decades. To keep up with rising laboratory. The field encompasses several specialized tech- costs of personnel, graduate education, equipment, and niques, ranging from the routine to the exotic, which are overhead, the NSF reports that institutions are increas- used in environments ranging from the ocean floor to the ingly reliant on funding from private philanthropy or surface of Mars. According to market analysis firm Market corporate research contracts. Nevertheless, in a welcome Research Engine (Deerfield Beach, FL), the global market trend for spectroscopy instrumentation manufacturers, for commercial instruments for atomic techniques including the NSF reported that academic institutions spent $2.1 atomic absorption (AA), inductively coupled plasma-opti- billion on capitalized research equipment in 2016 (the cal emission spectroscopy (ICP-OES), inductively coupled most recent year for which data is available), up 3% over plasma-mass spectrometry (ICP-MS), and x-ray fluorescence the prior year. The majority of those expenditures (87%) (XRF) analysis was expected to grow at 6% compounded an- were for instruments intended for life science, engineer- nual growth rate to exceed $6.5 billion by 2024. ing, and physical science applications. Against the backdrop of these broad trends, the diverse group of scientists who self-identify as spectroscopists are experiencing a mixed bag of good and not- so-good news. According to Spectroscopy’s 2018 salary survey (3), spectroscopists are earning more than ever before. The average annual salary for spectroscopists in 2018 was $91,129, a 7.6% increase over the prior year and the first time in the survey’s history that salaries surpassed the $90,000 mark. But the survey also found that spectroscopists may be working harder for that money, and deriving less satisfaction in the process. Stress levels and workloads were on the rise, and 13% of survey respondents said they were taking on extra work to aug- ment their earnings. The tools of the spectroscopy trade are as technologi- &HUWLĆHG5HIHUHQFH0DWHULDOV cally diverse as the range of applications in which they 899,61,50LG,5IURPD are used. Regardless of technique, however, most of the major commercial spectrometer manufacturers are con- World Leader tinuing their move toward smaller, more automated instruments (4). Often sold with preset analytical routines 'HHS89WR,QIUDUHG for common applications in specific industries, these in- )OXRUHVFHQFH struments are designed for use by less experienced lab 0LFURYROXPH PLFURSODWH personnel, or to help skilled users perform more com- 6WDUQD6FLHQWLĆF/WG ,62 plex operations in less time. Handheld or portable de- ,62,(&DFFUHGLWHG vices for field measurements are increasingly common, Starna Cells Inc. as are purpose-built spectroscopy-based analyzers for /LIHWLPH*XDUDQWHH (800) 228-4482 point-of-care clinical or biological measurements. These )DVWUHFDOLEUDWLRQVHUYLFH [email protected] types of instruments have been around for decades, of &XVWRP 2(0 www.starna.com course, but manufacturers are increasingly successful at 38 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

Trends and applications of atomic Laser Ablation and LIBS geologic carbon storage, determina- spectroscopy are largely driven by in the Spotlight tion of bitumen in oil sands, the use developments in key production The hottest trend in the field is ar- of AA spectroscopy to study ablated industries, many of them highly guably the continuing rise of two mass of samples in a laser-induced regulated, such as pharmaceuticals, laser-based methods: laser ablation plasma, and the use of a femtosec- foods and beverages, petrochemi- inductively coupled plasma-mass ond laser for tandem LA-ICP-MS/ cals, metals, and mining. Conse- spectrometry (LA-ICP-MS) and la- LIBS analysis, to list a few (11). quently, atomic spectroscopy is ser-induced breakdown spectroscopy also fundamentally important in (LIBS). LA-ICP-MS is enabling chem- Atomic Absorption the monitoring of the downstream ists to perform sensitive elemental Performance improvements in AA impacts of these industries on the and isotopic analysis directly on spectroscopy are helping to address ecosystem. The relentless drive to solid samples. A laser is focused on increased demand for sensitive met- improve the accuracy and precision the sample, generating fine particles als determinations with less sample of elemental spectroscopic analysis that are transported into a second- pretreatment. In an effort to devise has dramatically enhanced every ary excitation source of an ICP-MS a faster, simpler approach to trace step of the analytical process, from spectrometer for digestion and ion- analysis of toxic metals in livestock, sample preparation to regulatory ization. In the plasma torch, excited scientists at the Russian Academy of compliance. Advanced research ions are then transported into the MS Sciences and Novosibirsk National in atomic spectroscopy focuses on detector. Many of the mechanisms Research State University developed the development of improved tech- of laser ablation also power LIBS. a novel graphite furnace atomic niques for sample excitation and In this method, a short pulse from absorption spectroscopy (GFAAS) ionization, sample transport, inter- a high-power laser causes a high- method using two-stage probe at- ference elimination, and other fun- temperature micro-plasma to form omization (12). GFAAS is not widely damental areas. on the sample surface, exciting the used for direct trace analysis of electrons of the sample’s component whole blood, because of strong in- Glow Discharges atoms and ions. As the plasma cools terferences from the organic matrix. Several groups (6–8) are concentrat- and the atoms and ions return to a Bovine blood is especially problem- ing on the further development of ground state, the plasma emits light atic due to higher concentrations liquid-sampling or solution-cath- with discrete spectral peaks. LIBS of proteins and lipids compared to ode atmospheric-pressure glow dis- can detect every element in the peri- human blood. The two-probe atom- charge plasmas as versatile ionization odic table without requiring sample ization process enabled determina- sources for atomic and mass spec- preparation, making it applicable tion of trace levels of cadmium (Cd) trometry. The approach is based on to a wide range of sample matrices and lead (Pb) in bovine blood with a process in which the surface of liq- that include metals, semiconductors, minimal sample pretreatment, no uid passing through a glass capillary glasses, biological tissues, insulators, matrix suppression, and lower non- acts as the cathode of a direct-current plastics, soils, plants, soils, thin-paint selective absorption levels. Pharma- glow discharge. The passing current coating, and electronic materials. ceutical manufacturers are exploring vaporizes analyte-containing solu- LIBS in particular is command- high-resolution continuous source tions to produce gas-phase solutes ing new levels of attention, not only GFAAS for the sequential deter- that are then ionized in the plasma. among the atomic spectroscopy mination of Cd and Pb impurities Developers believe the technique world, but also across the analytical introduced by catalysts used in the could eventually offer a cheaper, chemistry community. Its vibrancy drug synthesis process (13). For AA simpler alternative to the higher- is evidenced by a marked increase in users who frequently need to switch powered plasma sources used in LIBS-related presentations at major among flame, graphite furnace and standard elemental mass spectrom- analytical science conferences such hydride atomization technologies, eters. Another area of heightened as Pittcon. In 2018, the Xth Inter- commercial systems that integrate activity in the alternative ionization national LIBS Conference ran in multiple techniques are now avail- source domain is dielectric barrier conjunction with SciX, the annual able from most of the major AA discharge ionization. The technique meeting and exhibition of the Fed- manufacturers. has shown potential as a single ion eration of Analytical Chemistry and source for both elemental quantifi- Spectroscopy Societies (FACSS), X-ray Analysis cation and molecular identification significantly increasing the num- X-ray fluorescence (XRF) spectros- on a single instrument platform. It ber of LIBS-related oral and poster copy is the other primary technique too offers reductions in operating presentations at the event. Speakers for elemental analysis among Spec- cost, power consumption, and ease- touched on a wide range of emerg- troscopy’s readership. Real-world ap- of-use in a range of environmental ing LIBS applications at SciX, in- plications of XRF abound because of sample matrices (9,10). cluding underwater measurement of its simplicity and nondestructive na- www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 39 ture. XRF equipment has long been used in field work, at before the solar wind samples could be analyzed. TXRF the production line, and in space exploration. Although was chosen to monitor the progress of contaminant re- general analytical chemistry and spectroscopy confer- moval because of its high surface sensitivity and non- ences typically offer workshops, short courses, and the destructive nature. TXRF has been explored as an alter- occasional oral session on XRF and related techniques, native to ICP-OES and ICP-MS in liquid analysis, because the premier showcase of advances and new applications is it offers faster measurement times, and quantification can the venerable Denver X-ray Conference, now gearing up be performed by internal standard addition without the for its 68th year. This event is an annual deep dive into need to set up calibration curves. Atsushi Ohbuchi and all facets of x-ray analysis, including XRF for elemental co-workers described applications of TXRF in the trace composition, x-ray diffraction for structural characteriza- element analysis of wastewater, finding its wide dynamic tion and phase identification structures, and a wide range range and direct analysis capabilities to be well suited for of other advanced methods for materials characterization, screening analysis. microscopy, surface analysis, and beyond. Last year’s Denver X-ray Conference, held August 6-10 Notable Applications of in Westminster, Colorado, presented a host of innova- Atomic Spectroscopy tive applications of XRF in elemental analysis (14). Non- Novel variations of ICP and ICP-MS have recently laboratory-based applications of XRF were prominent. emerged across a range of key industries, including nano- Joel O’Dwyer and colleagues at CSIRO Mineral Resources materials, biomedicine, agriculture/food, and environ- (Kirrawee, NSW, Australia) described a novel XRF ana- mental science. lyzer for both direct, on-stream elemental analysis and Single-particle (sp) ICP-MS is becoming increasingly routine in-plant batch analysis of process stream slurries. important in the characterization and sizing of metal- The system was found to have potential as a more sensi- lic engineered nanoparticles (15) in soil, drinking water, tive alternative to existing process analyzers, which are wastewater, and other environmental matrices. The tech- generally only able to measure concentrations above ap- nique offers superior elemental specificity, sizing reso- proximately 10 parts per million, and off-line or off-site lution, and sensitivity for metallic nanoparticles found analytical techniques, which can take hours or days to in a wide range pharmaceuticals, foods, personal care complete. A group from UHV Technologies (Lexington, products, and other consumer goods. Although certain KY) shared results of a study of an on-line XRF system as a lower-cost, in-line alternative to ICP-MS or AA for identifying metallic impurities introduced into pharmaceutical products during the manufacturing process. The performance of energy-dispersive (ED) XRF spectrometers (the kind most often used in field applications) has improved with the growing use of the silicon drift detector (SDD). As an alternative to the traditional silicon- lithium detector, SDDs offer better resolution and analytical performance at higher count rates. Maggi Loubser, a consulting scientist at GeoMag GeoChem (Meyerspark, Pretoria, South Africa) reported results from her tests comparing a handheld EDXRF analyzer with both a benchtop EDXRF system and a laboratory wavelength- dispersive XRF spectrometer. After calibrating all three systems with an identical set of reference materials, she found the handheld system’s capabilities to be generally comparable to that of the more expensive off-line systems. Quality Cells for Total-reflection x-ray fluorescence (TXRF) remains an area of growth in x-ray analysis and a number of inter- Quality results esting applications were highlighted at the conference. For example, a multi-institutional team from California )XOO\IXVHGFRQVWUXFWLRQ Institute of Technology, NASA, Arizona State University, 6WDUQD6FLHQWLĆF/WG and Loyola University used TXRF to assist in the clean- Transmission from 190 nm to 3800 nm ing of contaminated sample collectors used in the NASA Path lengths from 0.008 to 500 mm Starna Cells Inc. Genesis mission. Upon returning to Earth after collecting Volumes from 0.5μl to 170ml pristine solar wind ions in space from 2001 to 2004, the (800) 228-4482 spacecraft experienced a hard landing in which the solar :LGHUDQJHRIVWDQGDUGFHOOV [email protected] wind collectors were damaged and contaminated. The &XVWRPGHVLJQV www.starna.com surfaces of these collectors had to be thoroughly cleaned 40 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com nanoparticles are confirmed car- At minimum, most states require the range of standard IR spectrom- cinogens, little is currently known metals testing for the so-called Big eters while also enabling the obser- about their environmental cycling Four toxic metals: arsenic, cadmium, vation of higher-energy phenomena and transport into humans, so the lead, and mercury. AA, ICP-OES, and than can be measured with micro- use of sp-ICP-MS for this work will ICP-MS techniques are all suitable wave spectroscopy. This enables the likely continue to increase in the for metals analysis in cannabis sam- evaluation of vibrational behavior years ahead. ples, with each bringing its respective within subunits of large molecules, As the ability to sample and ana- benefits and limitations to the table. especially proteins, DNA, lipids, lyze individual human cells im- For laboratories that don’t require and other biomolecules. THz sys- proves, single-cell (sc) ICP-MS is high sample throughput, AA offers tems can be configured for a range providing a fast and sensitive way to high performance at the lowest cost. of real-world applications, includ- study elemental composition at the ICP with optical emission detection ing trace gas detection, layer thick- cellular level. Nanoparticles enter achieves comparable detection limits ness measurements, and high-speed cells not only through environmen- to AA with less sample processing, contact-free material and quality tal exposures, but also through cer- but at a higher operating cost. ICP- testing in production or remote en- tain pharmaceutical products, such MS offers superior sensitivity and vironments (21). as platinum-based chemotherapy throughput, but is much more ex- One traditional limitation of THz drugs. Sc-ICP-MS is increasingly pensive to purchase and operate. As spectroscopy has been its inability used to detect, measure, and deter- the industry matures and regulators to characterize single molecules, an mine bioavailability of key metal- requires the determination of more area of increasing interest in biol- containing species within the cell metals at lower concentrations, ICP- ogy and other fields. The long wave- (16,17). The method allows detec- MS’s role will likely increase (19,20). lengths of THz signals are tens of tion of discrete pulses of positively thousands of times larger than the charged ions in a time-resolved man- Trends in Molecular Spectroscopy size of typical molecules, making ner at microsecond data acquisition This discussion will focus primarily on it impossible to focus on just one. rates. It can monitor cells for intrin- spectroscopic methods for molecular However, a group at the University sic metal content and the uptake of analysis and characterization that in- of Tokyo’s Institute of Industrial ionic or nanoparticulate contami- volve the measurement of dispersed/ Science is working to overcome nates with minimal sample prepa- diffracted light across the ultravio- that problem. The team recently ration. Used in conjunction with let (UV) through far-infrared (IR) reported (22) successful entry into techniques such as flow cytometry, spectral regions. The worldwide the single-molecule regime with sc-ICP-MS opens the door to com- market for molecular spectroscopy a novel THz spectrometer design. bined cell number counting and cel- instrumentation and related sup- The system incorporates a single- lular metal mass quantification. plies was valued at $4.98 billion in molecule transistor, in which two It’s not often that a brand new 2018, and is projected to expand at a adjacent metal electrodes serving as multibillion-dollar industry ma- 6.6% compound annual growth rate the transistor’s source and drain are terializes virtually overnight. But to $6.85 billion by 2022, according positioned on a thin silicon wafer in such is the case with the legal can- to market research firm Market- a shape resembling a bowtie. They nabis market. With a recent Pew sandMarkets (Northbrook, IL). Key isolated single molecules of fuller- survey showing the approval of 62% drivers of new instrument sales are ene, and placed them into the sub- of Americans, 10 states and the Dis- said to be an increased worldwide nanometer gaps occurring between trict of Columbia have legalized the demand in the pharmaceutical and the source and drain. These elec- regulated sale of recreational can- biotechnology industries, as well as trodes help to focus the THz beam nabis, and 33 states permit the use new applications for emerging tech- on the isolated molecule. of the plant for prescribed medical niques such as terahertz spectros- treatment. The worldwide market for copy in healthcare. 2-D IR Spectroscopy legal cannabis sales in 2017 was val- Another area of increased recent in- ued at $9.5 billion (18), with the U.S. Terahertz (THz) Spectroscopy terest in the molecular arena is 2-D accounting for 90% of that amount. THz spectroscopy appeared in the IR spectroscopy, a powerful tool for Customer demands for product qual- late 1980s, and has more recently gleaning structural and dynamic ity and safety are requiring new ap- benefitted from higher-intensity information from a wide range of plications for analytical technology sources and more sensitive detec- systems of interest in biology and beyond those originally developed tors. The THz wavelength region materials science. The technique for drug screening and law enforce- falls between the microwave and subjects a sample to three excita- ment purposes, including tests for infrared spectral regions. Thus, tion pulses to create nonlinear po- potency, residual solvents, pesticide THz spectrometers can measure vi- larization. Measurement of the time contamination, and metals content. brational activity occurring beyond delay between the first two pulses www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 41 provides information on system dy- frared (SEAR 2-D IR) spectroscopy. Raman Spectroscopy namics. The third pulse probes the This technique combines localized Another of the most vibrant areas sample, creating emission data that surface plasmons with a reflection of molecular spectroscopy is one of reveals information on system evo- pump-probe geometry to improve the oldest. The Raman Effect was lution. By spreading IR spectra into monolayer sensitivity. first described 90 years ago, but the a second dimension, the technique Recently, a group at the University vibrational spectroscopic technique can reveal details about vibrational of Freiburg (24) reported what they harnessing that effect struggled for couplings and separate the effects of believe to be the first use of 2-D spec- much of the 20th century to find homo- and inhomogeneous dynam- troscopy on isolated molecular sys- real-world analytical application ics. The technique’s rich information tems. Despite the technique’s high in- due to technical challenges such content makes it an increasingly at- formation content and advantageous as interference from background tractive alternative to linear mid-IR femtosecond-scale time resolution, fluorescence. By the mid-1980s, ad- methods used in the study of mo- it has not been useful for studying vances in laser and detection tech- lecular structures, environmental individual quantum-mechanical ef- nologies caught up with the science dynamics, and structural kinetics. fects and thus been limited primar- behind Raman spectroscopy, and One of the most active groups in ily to the study of bulk liquid or solid the faith of the technique’s ardent 2-D spectroscopy is led by Martin materials. In this work, the scientists proponents has been redeemed with Zanni at the University of Wiscon- first synthesized the target molecu- a surge of new applications and sin-Madison. His team recently (23) lar compounds by adding individual commercial products. Today, a tech- addressed two common technical components one by one onto a fric- nique that not long ago was found challenges faced by spectroscopists tion-free substrate made of nanome- only in more sophisticated spectros- studying reactions at surfaces and ter-sized superfluid helium droplets. copy labs is now packaged within interfaces–low coverage of mole- This approach enabled observation of handheld pushbutton analyzers cules at the surface and discerning the molecule’s light-induced behavior used in the field by people with no between signals coming from the in the helium environment, which the scientific training whatsoever. bulk and the surface. Their solution: researchers expect to open new appli- Surface-enhanced Raman spec- a method called surface-enhanced cations of 2-D spectroscopy in photo- troscopy (SERS) has grown in promi- attenuated total reflection 2-D in- voltaic and optoelectronics research. nence across many application areas.

NEW AvaSpec-ULS4096CL-EVO EVOlutionary performance in high resolution measurements

• 4096 pixels for high resolution measurements like Plasma and LIBS • CMOS technology, ready for the next decade • Also available as OEM unit

[email protected] | www.avantes.com 42 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

Originally developed as a probe of tural and anisotropic IR analysis of two measurement surfaces within electrochemical reactions and the thin films and surfaces (30). Laser the instrument. Light passes directly adsorption of molecular species on sources and detection methods have through the sample over a pathlength metallic surfaces, SERS has been fueled the improvement of coherent determined by the distance between the embraced by a broader community Raman microscopy for biochemical two measurement surfaces–not by the of analysts who value its inherent analysis (31). Hyperspectral and mul- dimensions of a cuvette. Eliminating molecular specificity and single- tiplex imaging methods now achieve the cuvette also sidesteps the need to molecule detection capability. SERS higher chemical sensitivity and image dilute samples into larger buffer vol- has proven useful as a chemical contrast, without sacrificing video- umes, and, obviously, to clean the cu- sensor in field-based applications, rate imaging speeds. Spectroscopy vette after use. The shorter pathlengths where it is used to measure drugs, is also widely used for imaging on afforded by microvolume instruments explosives, heavy metals, toxic in- the macroscale. For example, laser- allow measurement across a wider dy- dustrial chemicals, and more (25). In induced luminescence spectroscopy namic range, thereby improving mea- the life sciences, SERS provides an is being used as a remote sensing surement accuracy, reducing time, and ultrasensitive biomolecular analyti- method in the exploration and dis- minimizing sample consumption. cal technique for small molecules, covery of new deposits of rare earth Often used as an extension of UV/ macromolecular proteins, and living elements used in energy, transporta- Vis (or vice versa), near-IR spectros- cells. SERS makes possible the direct, tion, computer, and telecommunica- copy is a well-established tool, not only label-free detection of molecules tions technologies (32). in life science but also in the pharma- through their intrinsic Raman fin- ceutical and medical device arena. gerprints, making it especially suit- Notable Applications of Near-IR’s analytical range, sampling able for characterizing dynamic 3-D Molecular Spectroscopy ease, operational simplicity, and com- structures like protein and lipid bi- As is true with atomic spectroscopy, the patibility with fiber-optic probes have layers as well as for studying biomol- most novel applications of molecular given rise to a host of rugged spec- ecules near metallic surfaces (26). techniques in recent years have arisen trometers customized for in-, on-, at-, in response to challenges or opportu- or near-line quality control of phar- Microscopy and Imaging nities driven by current events. Instru- maceutical and biopharmaceutical Significant advances continue to ment and application developers are production processes. The technique’s create new analytical possibili- exploring innovative uses of molecular versatility is helping that industry ex- ties through the coupling of vibra- spectroscopy to solve emerging ques- plore new directions to meet changing tional spectroscopy with various tions in biology, healthcare, environ- needs. For example, manufacturers of modes of microscopy and imaging. mental management, advanced mate- flu vaccines are increasingly seeking A number of specialized techniques rials, energy production, and beyond. cell-culture-based alternatives to poul- have emerged to perform IR and The life science/healthcare sector try eggs as growth media for vaccine Raman spectroscopic imaging with remains the most robust area of in- cultures. Cell-grown vaccines are of nanometer-scale resolution, includ- novation in molecular spectroscopy. great interest in the industry, because ing tip-enhanced Raman scattering Even the most mature techniques con- they can be administered to patients (TERS), IR scattering-type scan- tinue to evolve to meet the life science with poultry allergies, are less prone to ning near-field optical microscopy laboratory’s growing demand for more mutations, and are easier to scale up. (IR s-SNOM), atomic force micros- information from smaller sample vol- However, infrastructural and regula- copy infrared (AFM-IR) analysis, umes and lower concentrations. A tory issues must be overcome before and photo-induced force micros- decade ago, for example, UV/Vis spec- cell-based methods can be more widely copy (PiFM). These techniques are troscopy was at a disadvantage in cer- used in vaccine manufacturing. In a achieving unprecedented spatial tain applications, because it required proof-of-concept study (33), a group at resolution and chemical contrast in large sample volumes, and was accu- North Carolina State University tested a wide range of applications in ma- rate only with relatively high sample a near-IR method to measure the con- terials science, biomedical research, concentrations. In contrast, emerging centration of influenza virus in cells polymer research, and beyond (27). techniques based on microarrays were grown in a bioreactor. They found that AFM-IR is increasingly used to ex- finding increasing use due to their ease their probe provided near-real-time plore the mid-IR spectral region with of use and facility for extremely small data on viral concentrations in mul- spatial resolution beyond the diffrac- sample volumes. Microvolume UV/ tiple runs that rendered superior or tion limit. Groups are using the tech- Vis was a major breakthrough into the comparable accuracy to the standard nique for wide-ranging applications, life science realm. Microvolume spec- method, which can take an hour to such as subcellular-level imaging in trophotometers eliminate the need to produce results. fixed eukaryotic cells (28), the analy- use traditional cuvettes. Instead, the Another bioscience domain in which sis of atmospheric aerosol particles user introduces a tiny drop of sample optical spectroscopy continues to hold (29), and the nonpolarimetric struc- (often about 1 microliter) between great promise is the rapidly emerging www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 43 field of wearable technologies. The po- Oxycontin and morphine. Prescription and Raman spectroscopy are the pri- tential of spectroscopy as a non-invasive and non-prescription opioids are now mary spectroscopic techniques for the (that is, “through-the-skin”) monitor of responsible for 68% of U.S. drug over- identification of microplastics in the blood glucose in diabetes management dose deaths, according to the National environment (44). However, human has been an active area of research for Institute on Drug Abuse (39). Relatively consumption of microplastics isn’t al- decades, and the wearables boom is new on the scene is the synthetic opioid ways a result of environmental expo- sparking new ideas. Groups continue fentanyl, the highly potent painkiller fa- sure. One recent study (45) used micro- to explore various measurement modes mously linked to the accidental overdose Raman spectroscopy to determine the such as near-IR (34) and Raman (35–37) death of rock musician Prince. Fentanyl- presence of microplastics in mineral in the quest to improve the quality of related deaths have increased by 540% water sold in bottles (plastic and glass) care for a disease that affects an esti- in the U.S. since 2015 (40). A mere 2 mg and beverage cartons. Scientists found mated 425 million adults worldwide. of the drug is considered a lethal dose, small (50-500 micrometer) and very Beyond disease monitoring, wear- and the danger is not confined to inten- small (1-50 micrometer) fragments in able spectrometers are under study for tional users. Police officers, firefighters, every type of water, with nearly 80% of a wide range of non-clinical applica- and emergency medical personnel called all particles ranging between 5 and 20 tions. Recently a group at Drexel Uni- to the scene of an overdose or criminal micrometers–a size not detectable by versity developed a wearable headpiece activity face heightened risk of acciden- FT-IR microspectroscopy, which is gen- to capture functional near-IR images of tal inhalation or exposure through the erally limited to particles larger than brain-to-brain coupling–a way of mea- skin. As a result, instrument suppliers 20 micrometers. Despite Raman’s high suring and correlating brain responses are developing specialized spectroscopy profile in microplastics applications, its among multiple subjects during natural systems to help these non-scientist per- usefulness is still somewhat impaired verbal communication (38). The tech- sonnel protect themselves. Ion mobility by relatively slow analysis times, as well nique monitors oxygenated hemoglobin spectrometry is effective in the collec- as the age-old problem of fluorescence and deoxygenated hemoglobin in the tion and testing of invisible residues interference. One group is working to cerebral cortex. Because conventional from areas suspected of contamination, speed up the process, with improved techniques such as functional magnetic while IR and Raman systems have been detectors, automated mapping and resonance imaging (fMRI) require developed to identify unknown white library matching methods, and non- highly controlled laboratory environ- powders or liquids (41). linear methods that enable real-time ments that restrict the subjects’ mobil- The world reached an ominous en- measurement (46). ity, the near-IR method could provide vironmental milestone last year with advantages in neurolinguistics studies the first confirmed evidence that mi- Conclusion of natural human interactions. Other croplastics have entered the human In the more than 200 years since Jo- scientists have recently sought to ex- food chain. A study (42) conducted by seph von Fraunhofer developed the tend near-IR’s non-invasive capabilities the Environment Agency Austria used first modern spectroscope, scientists for unobtrusive measurement of fitness FT-IR microspectroscopy to confirm have never stopped searching for new indicators. A group of engineers at the the presence of polypropylene, poly- ways to make it better. Spectroscopy University of British Columbia, for ex- ethylene terephthalate, and other plas- has returned the favor many times over, ample, have recently teamed up with a tic particulates in fecal samples from playing a critical role in the discovery sports physician to develop a health- eight participants from Europe, Japan, and development of new materials, monitoring smart garment using em- and Russia. Based on this study, the medicines, foods, chemicals, fuels, and bedded near-IR sensors and software agency hypothesized that more than other products intended to improve our to measure local muscle metabolism. half the world population may have standard of living. The introduction of The idea is to help ensure an athlete microplastics in their system. These <5 innovations such as the microproces- trains at the appropriate level for their mm particles, fibers, and shards of de- sor, laser, and advanced detectors dra- physical condition at any given point graded plastic have been found around matically sped up the pace of progress in time. For athletes recovering from the world in natural waters, beaches, in the mid-to-late 20th century, launch- an injury, metabolic data could help Arctic sea ice, agricultural lands, and ing the continuing trend toward com- optimize a training regimen that pro- the air. They are small enough to be mercial instruments combining high motes healing, without overtaxing the ingested by tiny marine lifeforms, but performance with a high degree of au- wearer. Conversely, the method could not necessarily to pass through without tomation. Even as more lay-level users tell coaches when it is safe to push a causing harm. They can harm organs begin to wield spectrometer-based de- healthy athlete harder when training and release chemicals that affect im- vices in their respective professions, the for competition. munity, growth, and reproduction (43). field will always be populated by spec- Society may be increasingly receptive Just as atomic spectroscopy has troscopists with the training, insights, to legalizing cannabis, but the opposite found a new niche in measuring the and tenacity required to extract high- is true when it comes to the over-pre- impact of metallic particles on the en- quality data from complex samples and scription and abuse of opioids such as vironment and human health, FT-IR to translate that raw data into useful 44 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com information. Thus, it is safe to assume Jakubowski, and T. Schwerdtle, Metal- Proceedings Volume 10116: MOEMS that spectroscopic instrumentation and lomics 10(1), 73–76 (2018). and Miniaturized Systems XVI, SPIE, applications will continue to evolve and (17) L. Amable, C. Stephan, S. Smith and R. Bellingham, WA. improve for the foreseeable future. Merrified, “An Introduction to Single- (35) Y. Zheng, X. Zhu, Z. Wang, Z. Hou, F. Gao, Cell ICP-MS Analysis,” white paper, R. Nie, X. Cui, J. She, and B. Peng, Chin. References PerkinElmer, Inc., Waltham, MA (2017). Opt. Lett. 15(8), o83001 (2017). (1) “Toll on Science and Research Mounts (18) “In 2017 and Beyond, U.S. Enjoys the (36) S.M. Lundsgaard-Nielsen, A. Pors, S.O. as Government Shutdown Continues,” Highest Legal Cannabis Market Share Banke, J.E. Henriksen, D.K. Hepp, and A.Blinder, New York Times, Jan. 5, 2019. Worldwide,” Thomas Pellechia, Forbes, A. Weber, PLOS One, Published: May 11, (2) National Science Board Science & En- June 26, 2018. 2018, https://doi.org/10.1371/journal. gineering Indicators 2018, National Sci- (19) J. Nelson, C. Jones and N. Drvodelic, pone.0197134). ence Foundation, Alexandria, VA. Cannabis Science and Technology 1(2) (37) S.P. Singh, S. Mukherjee, L.H. Galindo, (3) L. Botcherby, Spectroscopy 33(3), 24–33 20–25 (2018). PT.C. So, R.R. Dasari, U.Z. Khan, R. Kan- (2018). (20) A.P. Fornadel, D.L. Davis, R.H. Clifford, nan, A. Upendran, and J.W. Kang, Anal. (4) H. Mark and M. Bradley, Spectroscopy and S.A. Kuzdzal, Cannabis Science and Bioanal. Chem. 410, 6469 (2018). 33(5), 28–50 (2018). Technology 1(1) 36–41 (2018). (38) Y. Liu, Sci. Rep. 7, 43293; doi: 10.1038/ (5) “Winners of the 2018 Scientists’ (21) A. Deninger, L. Gray and T. Paasch- srep43293 (2017). Choice Awards for General Lab, Colberg, Photonics Spectra 52(8), 50 (39) Overdose Drug Rates, revised January Separations, and Spectroscopy An- (2018). 2019, National Institute on Drug Abuse, nounced at Pittcon,” selectcience. (22) S. Du, K. Yoshida, Y. Zhang, I. Hamada, National Institutes of Health, Bethesda, net, https://www.selectscience.net/ and K. Hirakawa, Nat. Photonics 12, MD. https://www.drugabuse.gov/re- scientistschoiceawards/PRDetails. 608–612 (2108). lated-topics/trends-statistics/overdose- aspx?artID=45849 (23) M.K. Petti, J.S. Ostrander, V. Saraswat, death-rates. (6) A.J. Schwartz, K.L. Williams, G.M. Hieftje, E.R. Birdsall, K.L. Rich, J.P. Lomont, M.S. (40) “The First Count of Fentanyl Deaths in and J.T. Shelley, Anal. Chim. Acta 950, Arnold, and M.T. Zanni, J. Chem. Phys. 2016: Up 540% in Three Years,” J. Katz, 119 –128 (2017). 150, 024707 (2019). New York Times, Sept. 2, 2017. (7) S. Schroeder, “Development of a New (24) L. Bruder, U. Bangert, M. Binz, D. Uhl, (41) FireRescue1.com, Oct. 10, 2017. Plasma Spectrochemical Emission R. Vexiau, N. Bouloufa-Maafa, O. Dulieu (42) “Microplastics found in human stools for Source for On-line Elemental Analysis,” and F. Stienkemeier, Nat. Commun. 9, the first time,” F. Harvey and J. Watts, presentation at InnoTech Alberta, Sept. 4823 (2018). The Guardian, Oct. 22, 2018. 9–13, 2018, Rossland, British Columbia, (25) P.A. Mosier-Boss, Nanomaterials 7(6), (43) “From Fish to Humans, a Microplastic In- Canada. 142 (2017). vasion May be Taking a Toll,” A. Thomp- (8) R.K. Marcus, C.D. Quarles Jr., C.J. Bari- (26) I. Bruzas, W. Lum, Z. Gorunmez, and L. son, Scientific American, Sept. 4, 2018. naga, A.J. Carado, and D.W. Koppenaal, Sagle, Analyst 143, 3990–4008 (2018). (44) L. Mai, L.J. Bao, L. Shi, C.S. Wong, and Anal. Chem. 83(7), 2425–2429 (2011). (27) L. Xiao and Z.D. Schultz, Anal. Chem. 90, E.Y. Zeng, Environ. Sci. Pollut. Res. Int. (9) K. Zheng, M.J. Dolan Jr., P.J. Haferl, H. Ba- 440–458 (2018). 25(12), 11319–11332 (2018). diei, and K. Jorabchi, Anal. Chem. 90(3), (28) L. Quaroni, K. Pogoda, J. Wiltowska- (45) D. Schymanski, C. Goldbeck, H.U. 2148-2154 (2018). Zuber and W.M. Kwiatek, RSC Adv. 8, Humpf, and P. Fürst, Water Research (10) X. Wu, W. Yang, M. Liu, X. Hou and C. 2786–2794 (2018). 129, 154–162 (2018). Zheng, J. Anal. At. Spectrom. 26, 1204– (29) A.L. Bondy, R.M. Kirpes, R.L. Merzel, (46) C.F. Araujo, M.M. Nolasco, A.M.P. Ri- 1209 (2011). M.M. Banaszak Holl, A.P. Ault, Anal. beiro, and P.J.A. Ribeiro-Claro, Water (11) Final program, SciX 2018, Oct. 21-26, Chem. 89(17), 8594–8598 (2017). Research 142, 426–440 (2018). ◾ 2018, Atlanta, GA. (30) K. Hinrichs and T. Shaykhutdinov, Appl. (12) A.V. Volzhenin, N.I. Petrova, T.V. Skiba, Spectrosc. 72(6), 817–832 (2018). and A.I. Saprykin, Microchem. J. 141, (31) T. Gottschall, T. Meyer, M. Schmitt, J. Michael MacRae writes about 210–214 (2018). Popp, J Limpert, and A. Tünnermann, science, technology, and society. A for- (13) A.C.M. Aleluia, F.A. de Santana, G.C. TrACs 102, 103–109 (2018). mer editor of Spectroscopy and its sister Brandao, and S.L.C. Ferreira, Microchem. (32) S. Lorenz, J. Beyer, M. Fuchs, P. Seidel, publication, LCGC, he lives in Portland, J. 130, 157–161 (2017). D. Turner, J. Heitmann, and R. Gloaguen, Oregon. Direct correspondence to: (14) Conference Program, 67th Annual Den- Remote Sens. 11(1), 21 (2019). [email protected]. ver Conference on Applications of X-ray (33) L. Vann and J.D. Sheppard, Bioprocess Analysis, Aug. 6-10, 2018, Westminster, International, September 15, 2018. CO, http://www.dxcicdd.com/18/sum- (34) J. Bae, V.V. Druzhin, A.G. Anikanov, S.V. mary.htm Afanasyev, A. Shchekin, A.S. Medvedev, For more information on this topic, (15) C. Stephan and R. Thomas, Spectros- A.V. Morozov, D. Kim, S.K. Kim, H. Moon, please visit our homepage at: copy 32(3), 12–25 (2017). H. Jang, J. Shim, and J. Park, presenta- www.spectroscopyonline.com (16) S. Meyer, A. López-Serrano, H. Mitze, N. tion at OPTO 2017, San Francisco, CA, www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 45

SPECTROSCOPY SPOTLIGHT

THE LIBS ADVANTAGE IN MINING AND ENERGY APPLICATIONS

Laser-induced breakdown spectroscopy (LIBS) has seen significant advances and expanded adoption in recent years. In particular, LIBS is being implemented in industrial applications, where it can provide important advantages over other techniques. Mohamad Sabsabi, of the National Research Council (NRC) of Canada, has been leading programs to research and implement the use of LIBS in mining and energy applications. He recently spoke to us about this work.

Laura Bush

You recently used LIBS to analyze gold often include quartz, pyrite, chalcopyrite, generator, and a high voltage source for in rock samples (1). How did this project sphalerite, and arsenopyrite), but the el- the intensifier. In the last six years, the come about? emental composition is out of reach of advent of new enabling components Exploration of precious metals is very this technique. XRF has been used suc- has encouraged the NRC LIBS team to challenging, because the cutoff grade cessfully for determining the concentra- renew its interest and reconsider the continues to decrease as the value of tion of some basic metals, such as copper, project within the newly initiated NRC metals increases. The gold mining in- zinc, and nickel, but it is inadequate for High Efficiency Mining program and in dustry is looking for technologies that quantifying gold concentration, because collaboration with major Canadian gold allow fast, in situ analysis to allow them of its low sensitivity and poor limit of mining companies, the Université Laval, to make decisions in the field, such as detection (LOD). In addition, portable in Quebec City, and the Institut National adjusting sampling plans, testing hy- X-ray fluorescence (XRF) systems are not de Recherche Scientifique (INRS). potheses based on ongoing results, and sensitive enough for gold detection in the making fast decisions on exploration ppm range required by the industry, and What were the main obstacles you had to work, especially drilling and sampling. XRF suffers from interference with zinc overcome? This is particularly important for re- and iron, which give false values for gold Analyzing a mineral ore sample is not mote locations, where the logistics of and compromises its determination. an easy task for the analytical chem- getting samples to a laboratory may be LIBS appears to be a good candidate ist. There are very few works in the slow and demanding. for gold detection. The idea of using literature devoted to LIBS analysis of So, the mining industry is on the LIBS for gold is not new. In our labora- gold in ore samples. There are many lookout for new technologies that tory, we pioneered the work 24 years ago, challenges related to such an investi- meet their cost reduction needs. One in collaboration with the Centre de Re- gation, including 1) the heterogeneity of these innovative technologies, the cherches Minerales (CRM), now called of the gold distribution and the lack of development of which would be a major COREM, in Quebec. We showed the natural gold ore reference samples, 2) breakthrough, is the measurement of proof of concept of feasibility in the labo- variation in the mineralogical matrix precious metal concentrations in ore, ratory in terms of sensitivity and quan- in ore samples, 3) the fact that gold is in real time and on site, during various tification on synthetic samples. However, embedded in several matrices—silica, stages of exploration and mining. In the LIBS components at that time were quartz-chlorite, and pyrite, with the the case of gold, this technology needs not adequate for on site applications in particle size varying from sub μm up to be able to measure an average con- terms of robustness, portability, and to few tens of μm, 4) the complexity of centration down to ~1 ppm, because performance. At the time, for the detec- their natural mixing matrices for ana- gold is still worth extracting at such a tion system we were using an intensified lytical purposes, 5) the complexity of low concentration. Existing technology photodiode array (IPDA)—which is now characterization of the laser induced for the direct analysis of gold in solid outdated and has been replaced by an in- plasmas, and 6) sensitivity to the sub- samples, such as infrared (IR) spec- tensified charge coupled device (ICCD)— ppm level of gold concentration, which troscopy, allows determination of the that was bulky and needed a chiller for requires optimized components and

mineralogy of the rock samples (which cooling the photodiode array, a delay conditions for gold detection. TOM FULLUM/GETTY IMAGES 46 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

In terms of a functional LIBS-based samples. When LIBS is compared to about that work? device, these challenges translate into: fire assaying or atomic absorption The Athabasca oil sands in Canada are 1) adequately sampling the surface of (AA) for the analysis of homogenous considered to be the largest oil sand the mineral to accurately evaluate the samples, there is a good agreement be- reserves in the world. Oil sands are gold concentration, 2) resolving the tween the results obtained by the two heterogeneous mixtures composed of matrix effects that result in variations techniques for the same sample. How- about 4−18% of bitumen, about 65−80% of the spectroscopic signal of gold with ever, on core samples or bulky rocks, of mineral solids, and about 2−15% of the compositions of the ore, 3) finding the discrepancies are more related water. Oil produced from oil sands by ways to prepare synthetic samples to to the inhomogeneity of the samples, open pit mining methods involves the match natural rock samples for quan- rather than disagreement between the basic steps of mining the oil sands, bi- titative analysis, 4) reconciling bulk two techniques. This has been verified tumen recovery by flotation, upgrading analysis by conventional techniques by conventional techniques on the two for synthetic oil, and finally refining. based on wet chemistry with the sur- halves of the same core being analyzed Prior to the recovery of bitumen by face analysis given by LIBS, 5) develop- by the same technique. Our work con- flotation, it is important to character- ing strategic sampling plans to ensure stitutes a first step toward determining ize the oil sands feedstock ore content representative sampling to build confi- gold concentration in practical mineral to optimize the process, and make a dence in the analysis, 6) having appro- samples using LIBS. It shows that LIBS decision from the perspectives of the priate depth of field to avoid problems can detect gold in the ppm range and environment and economic value. with surface roughness, and 7) resolv- provides a proof of concept for quan- These measurements can be done ing the water effect. titative analysis of gold ore samples in in the laboratory, or on a conveyor to reference materials, whether synthetic monitor the feedstock. However, cur- What were your main findings? or powdered samples. rent methods for assessing oil sands We have used LIBS for evaluating the content are time consuming and labor concentration of gold in mineral sam- What are the next steps in this work? intensive, as well as difficult to con- ples of practical interest, namely fine As pointed out above, several ques- trol, because of the complexity and and granular powders, and drill cores. tions remain to be addressed. Some of heterogeneity of the samples that con- The calibration curve was established the main questions are the following: 1) tain different particle sizes and several using 44 synthetic samples made of Can the calibration curve established minerals. The industry standard for compressed powders of different com- from compressed powders be used for determining bitumen, water, and sol- positions containing a quasi-uniform solid samples such as granular powder ids contents of oil sands ore samples distribution of gold. The samples rep- or rocks? 2) Does the cutting process of is the Dean−Stark extraction method. resent the types of ore we find in the drill cores or rocks affect the gold con- Extraction of bitumen from the solids Canadian Shield. We found that the centration at the surface of the sample? takes several hours to complete. Once calibration curve for the Au I 267.59 3) How can we automatically identify the three components have been sepa- nm line splits into two branches: one the gold concentration independently rated, the clean and dry minerals can for Si-rich samples (5% iron), and one of the matrix? 4) How can we scan the be identified and quantified by a vari- for Fe-rich samples (15% iron), with rock samples in an optimal way, so as to ety of techniques, including elemental limits of detection of 0.8 ppm and 1.5 minimize the effects of heterogeneity of analysis by inductively coupled plasma ppm, respectively, thus nearly meet- the gold concentration with a minimal optical emission spectrometry (ICP- ing the needs of the mining industry number of laser shots? 5) How does the OES), and mineralogy by X-ray dif- in term of the detection limit for the water content or dust on the surface af- fraction (XRD). Given the difficulties determination of gold concentration fect the analysis? 6) How does the water mentioned above, the oil sand indus- (~1 ppm). We showed that normaliz- content affect the analysis for the chips try needs a breakthrough technology ing the gold line intensity with respect sample? 7) What is the best sampling able to determine the bitumen content to the integrated spectrum intensity pattern to minimize the number of quickly and without sample prepara- or with respect to the spectral back- shots without compromising the re- tion, either in the laboratory or online. ground (plasma continuum emission) producibility of the measurement and LIBS appears to be a potential candi- close to the gold line improves the re- still ensure representative sampling? 8) date technique to meet that need. We gression fit of the calibration curves, Is there a way to address the issue of investigated the potential of LIBS for as compared to not normalizing. The standards for calibration in particular this application. use of one branch or the other of the for higher concentrations (100 ppm and calibration curve can be determined above)? All these questions are cur- What were your main findings? from the continuum generated by rently under investigation. We investigated the application of LIBS iron in the samples. In practical cases, to Athabasca oil sands samples to find because the gold is particulate in the You have also used LIBS for the rapid a correlation between LIBS spectra and ore, the LOD for gold in rock samples determination of bitumen content in bitumen content. In particular, we fo- can be even lower in inhomogenous Athabasca oil sands (2). Can you tell us cused on evaluating the potential of www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 47

LIBS to meet the requirements of the ponents and the increase in hyphenated the NRC in 1992 where he initiated activi- oil sands industry in terms of analyti- systems that will enable more sophisti- ties in laser plasma spectroscopy and built cal performance for the determination cated analysis and thereby, boost market a team among the most active in this field. of the bitumen content without sample growth. Sabsabi and his team have succeeded preparation. The analysis of bitumen in pioneering and implementing laser- ore samples is very challenging be- References induced breakdown spectroscopy (LIBS) cause of the heterogeneous nature of (1) K. Rifai, M. Laflamme, M. Constantin, F. Vidal, technology for many applications. In par- the mixture of bitumen, water, and M. Sabsabi, A. Blouin, P. Bouchard, K. Fytas, ticular, the LIBS method developed by the mineral content. A qualitative study M. Castello, and B.N. Kamwa, Spectrochim. NRC LIBS team has been implemented in was done first, and then a multivariate Acta, Part B 134, 33–41 (2017). the five continents for the analysis of mol- quantitative method was performed to (2) A. Harhira, J. El Haddad, A. Blouin, and M. ten materials because there is no alterna- assess the feasibility of determining Sabsabi, Energy Fuels 32, 3189−3193 (2018). tive conventional method. He initiated and bitumen by LIBS. The results show a led, for four years, the NRC High Efficiency good correlation between LIBS spectra Mining (HEM) program that aims to bring and bitumen content, and a prediction Mohamad improvements throughout the mining averaged absolute error <1%. Our re- Sabsabi value chain by developing advanced sen- sults showed that the combination of is a principal research sors, process technologies, and advanced LIBS and chemometrics proved to be officer in the Energy, materials. From Sabsabi’s inventions, there a novel rapid quantitative method for Mining, and have been two spin-off companies and assessing bitumen in oil sands with- Environmental Research six technology transfers in applications of Mohamad Sabsabi out sample preparation and with only Center at the National LIBS in the mining, agricultural, metallurgi- a few calibration samples. The method Research Council (NRC) of Canada. He cal, pharmaceutical, and manufacturing represents a real alternative to meth- received his Ph.D. in physics from the industries. He holds 18 patents and has ods traditionally used in the oil sands Université de Paris (France) in 1988. more than 500 publications (papers and industry. Moreover, given that the After conducting postdoctoral research conference presentations) covering funda- LIBS fingerprint is information-rich, on thermal plasmas at the Université de mental aspects and industrial applications this method could also provide ad- Sherbrooke, in Quebec, Canada, he joined of laser-induced plasmas. ditional information about elemental solid composition, and, therefore, some key elements related to either clays or quartz signature evaluation. So several potential applications can be targeted for rapidly assessing oil sands on a conveyor to evaluate the feedstock grade, or ore grades, either in the laboratory, at-line, or online.

Do you plan to develop this work further? Future work includes XRF and XRD analyses to validate the feasibility of the LIBS technique for minerals and clays estimation. More samples with wide mineralogical types and bitumen composition will be studied to investi- gate various sampling strategies, and to improve the precision and the accuracy of bitumen prediction.

Are you planning to develop LIBS for any other areas of research? In our laboratory, we will continue working on improving the analytical performance of LIBS to be implemented as a technology for problems in society, with a focus on natural resources. We will keep taking into account the discovery of new enabling tools and com- 48 Molecular Spectroscopy ADVERTISEMENT

Photonics Applications in Environmental Sciences

Avantes, Inc.

Ecosystems around the world face growing threats from industrialization, growing populations, and increasing urbanization. Not surprisingly, researchers, scientists, and governments are investigating tools for monitoring and preventing these environmental hazards. As all sorts of industries advance in the global marketplace, the need for ecological monitoring technology advances as well. Several spectroscopic measurement techniques are proving to be very effective and versatile for environmental applications.

Contamination monitoring Researchers with the Institute of Solar Energy at the Technical University of Madrid, Spain, trust the Avantes AvaSpec-2048- USB2-UA in their research into the use of high-powered UV LEDs as an excitation source for continuous-use fl uorescence testing. LED technology has advanced recently, making these Figure 1: Water treatment cost eff ective bulbs an appealing alternative. Traditional incandescent mercury bulbs produce a large amount of heat compared to Oceanographic research LEDs, which, combined with their short life, make continuous Th e world’s oceans produce more than half of the oxygen in our use impossible. atmosphere. Protecting our oceans is vital, and researchers are Th ese scientists are working to bring real-time, continuous increasingly using spectroscopy to monitor the health of the world’s monitoring for hydrocarbon pollution to fruition, using LEDs seas and oceans. instead of traditional bulbs. A group of researchers studying ocean and coastal waterways has been developing models to anticipate intense phytoplankton Water treatment blooms using irradiance spectroscopy. Th ese harmful blooming Th e Avantes AvaSpec-ULS2048-USB2 is trusted by researchers at the events adversely aff ect ecosystems and human health as well. Solar Energy Research Center and Chemical Engineering Department Using unmanned aerial vehicles fi tted with an Avantes dual- of the University of Almeria, Spain, in the study of LED light sources channel spectro-radiometry solution covering 360 to 1000 nm, for tertiary wastewater treatment processes. the team was able to derive fi ne-resolution spectral data and Tertiary treatment is the fi nal stage of wastewater treatment that obtain timely information on bloom magnitude, making spectral removes lingering inorganic compounds and other substances such bloom monitoring during algal bloom season a possibility. as nitrogen and phosphorous. Th is photocatalytic process, employing UVA radiation at 365, 385, and 400 nm, is the photo-Fenton reaction References in which radiation causes a rapid reaction between hydrogen peroxide (1) J.A.S. Pérez et al., Photoch Photobio Sci, 16, 72–78 (2017). and iron. (2) F.J. Arques-Orobon et al. Sensors (Basel) 16 (3) , 293. (2016). Historically, the photo-Fenton reaction relied on solar radiation (3) S. A. Khan, M. Ibrahim, et. al., J Chem-NY, 2013, (2013). as the source of catalytic radiation, but weather conditions and solar doi:10.1155/2013/894020. cycles make artifi cial illumination an attractive alternative. Recently, (4) S. Shang et al., Remote Sens Environ, 198, 85–94, (2017). this has been accomplished using mercury lamps, which have a limited lifespan and high cost associated with them. Th e Spanish researchers Avantes USA are testing the eff ectiveness of newly available LED light sources for 500 S. Arthur Ave., Unit 500, Louisville, CO 80027 UV radiation with positive results. LED bulbs are less expensive than tel. +1 (303)-410-8668 traditional incandescent bulbs and have a longer life span. www.avantes.com www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 49 Calendar of Events May 2019 July 2019 October 2019

28–30 North American Workshop 21–24 2019 NACRW 8–11 ACIL 2019 Annual Meeting on Laser Ablation 2019 Naples, FL Nashville, TN Austin, TX www.nacrw.org www.acil.org www.jsg.utexas.edu/nawla2019/ August 2019 13–18 SciX Conference Palm Springs, CA 30–June 1 American Chemical 4–8 71st American Association www.scixconference.org Society Middle Atlantic Regional for Clinical Chemistry (AACC) Meeting Annual Scientific Meeting & Baltimore, MD Clinical Lab Expo 15–16 Gulf Coast Conference https://www.acs.org/content/acs/en/ Anaheim, CA Galveston, TX meetings/regional/middle-atlantic http://www.2019aacc.org/ www.gulfcoastconference.com

June 2019 5–9 2019 National Environmental Monitoring Conference (NEMC) 16–19 American Chemical 2–6 ASMS 2019 Jacksonville, FL Society Midwest Regional Atlanta, GA http://www.nemc.us Meeting https://www.asms.org Wichita, KS 5–9 Denver X-ray Conference https://www.acs.org/content/acs/en/ Lombard, IL meetings/regional/midwest.html 4–7 American Chemical Society www.dxcicdd.com Central Regional Meeting November 2019 Midland, MI

https://www.acs.org/content/acs/en/ 11–15 SPIE Optics + Photonics 3–6 American Association of San Diego, CA meetings/regional/central Pharmaceutical Scientists 2019 http://spie.org/conferences-and-exhibi- PHARMSCI 360 tions/optics-and-photonics San Antonio, TX 11–13 American Chemical Society https://www.aaps.org/pharmsci/ Green Chemistry & Engineering annual-meeting Conference & International 25–29 American Chemical Society Fall 2019 National Conference on Green and 8–20 Eastern Analytical Sustainable Chemistry Meeting & Expo San Diego, CA Symposium and Exhibition Reston, VA Princeton, NJ http://www.gcande.org https://www.acs.org/content/acs/en/ meetings/national-meeting eas.org

23–27 SPIE European Conference September 2019 December 2019 on Biomedical Optics 8–13 COLA 2019: 1–6 2019 Materials Research So- Munich, Germany ciety Fall Meeting and Exhibit http://www.spie.org/conferences-and- The 15th International Conference on Laser Ablation Boston, MA exhibitions/european-conferences-on- www.mrs.org/fall2019 biomedical-optics?SSO=1 Maui, HI https://cola2019.org/ March 2020

24–27 Laser World of Photonics 24–26 Spectro Expo 1–5 Pittcon Conference & Expo Amsterdam, The Netherlands Munich, Germany 2020 https://world-of-photonics.com/ www.spectroexpo.com Chicago, IL index-2.html https://pittcon.org 50 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com Short Courses April 2019 5 Laser Beam Analysis, Propagation, 6 Introduction to Ultrafast and Shaping Techniques Pulse Shaping—Principles and 29 April–3 May ICDD X-ray Conference on Lasers and Electro-Optics Applications Fluorescence Clinic 2019 (CLEO) Conference on Lasers and Electro-Optics Newtown Square, PA San Jose, CA (CLEO) www.icdd.com/index.php/icdd-xrf www.cleoconference.org/home/pro- San Jose, CA gram/short-courses/sc157 www.cleoconference.org/home/program/ May 2019 short-courses/sc352

5 Basics of Quantum Optics for 5 How to Start a Company Quantum-Enabled Technologies Conference on Lasers and Electro-Optics 6 Laser Radar and Remote Conference on Lasers and Electro-Optics (CLEO) Sensing: An Application-oriented (CLEO) San Jose, CA Introduction San Jose, CA www.cleoconference.org/home/pro- Conference on Lasers and Electro-Optics www.cleoconference.org/home/program/ gram/short-courses/sc456 (CLEO) short-courses/sc479 San Jose, CA www.cleoconference.org/home/pro- 5 Microresonator based Optical gram/short-courses/sc477 5 Foundations of Nonlinear Optics Frequency Comb and Photonic Conference on Lasers and Electro-Optics Waveguide Supercontinuum Sources (CLEO) Conference on Lasers and Electro-Optics 6 High Power Fiber Lasers and San Jose, CA (CLEO) Amplifiers www.cleoconference.org/home/pro- San Jose, CA Conference on Lasers and Electro-Optics gram/short-courses/sc149 www.cleoconference.org/home/ (CLEO) program/short-courses/sc478/ San Jose, CA www.cleoconference.org/home/pro- 5 Metasurface Flat Optics: A New gram/short-courses/sc270 Paradigm for Optical Components 6 Coherent Mid-IR Light: Generation Design and Manufacturing and Applications June 2019 Conference on Lasers and Electro-Optics Conference on Lasers and Electro-Optics (CLEO) (CLEO) 1–2 Bioinformatics for Protein San Jose, CA San Jose, CA Identification www.cleoconference.org/home/program/ www.cleoconference.org/home/program/ Atlanta, GA short-courses/sc475 short-courses/sc361 www.asms.org/docs/default-source/ conference-short-course-descriptions/ updated_01-bioinformatics-for-program- 5 Silicon Integrated Nanophotonics 6 Fundamentals and Applications of identification.pdf?sfvrsn=2 Conference on Lasers and Electro-Optics VCSELs (CLEO) Conference on Lasers and Electro-Optics San Jose, CA (CLEO) 14 Spectroscopy Simplified – www.cleoconference.org/home/pro- San Jose, CA A Short Course on Infrared and gram/short-courses/sc466 www.cleoconference.org/home/pro- Raman Spectroscopy gram/short-courses/sc481 Paisley, UK www.rsc.org/events/detail/31561/spec- 5 Frontiers of Guided Wave Nonlinear troscopy-simplified-a-short-course-on- Optics 6 Plasmonics infrared-and-raman-spectroscopy Conference on Lasers and Electro-Optics Conference on Lasers and Electro-Optics (CLEO) (CLEO) www.cleoconference.org/home/program/ San Jose, CA short-courses/sc396 www.cleoconference.org/home/program/ short-courses/sc376 www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 51 Call for Papers

Spectroscopy invites researchers to submit their work for publication.

eaders interested in sharing Use Chemical Abstracts Service X-ray Spectroscopy supplement, the results of their research Source Index for journal abbrevia- November 2019 R with more than 27,000 other tions. Use the following format for Submission deadlines: spectroscopists are encouraged to references: Abstracts: June 7, 2019 submit manuscripts for review and (1) R. Salzer and H.W. Siesler, Infra- Manuscripts: August 16, 2019 possible publication. red and Raman Spectroscopic Im- Spectroscopy publishes articles aging (Wiley-VCH, Weinheim, Current Trends in Mass dealing with practical applications 2009), pp. 90–103. Spectrometry supplement series of modern spectroscopic techniques (2) P. Matousek, Appl. Spectrosc. 60, Our supplement series on mass spec- and instrumentation. Contributed 1341 (2006). trometry appears four times a year: manuscripts commonly address any in March, May, July, and October. of the following topics: Author Benefits Manuscripts for this series should • emerging techniques Publishing your work in Spectros- be approximately 3500–4500 words • new applications of spectroscopic copy has many advantages. The size long, including an abstract of ap- instrumentation of Spectroscopy ’s audience, with more proximately 150–200 words, plus up • current trends in hot research than 27,000 readers, makes Spectros- to eight figures and tables. We are areas copy the ideal vehicle for communicat- still accepting submissions for the • improved methods for common ing information of broad significance following issues: applications to the spectroscopy community. Con- • data-handling strategies tributed technical papers published in Submission Deadlines: • solutions to sample-handling Spectroscopy have passed a thorough problems. peer-review process. Our pool of refer- October 2019 issue The full range of atomic spectros- ees includes the members of our distin- Abstracts: April 1, 2019 copy, molecular spectroscopy, and guished Editorial Advisory Board. Manuscripts: June 7, 2019 mass spectrometry techniques is suitable for coverage in Spectroscopy. Special Supplements March 2020 issue A number of supplemental issues are Abstracts: October 5, 2019 Manuscript Preparation planned for 2019, for which we also invite Manuscripts: December 17, 2019 Manuscripts for regular issues contributions. Manuscripts for the sup- should be approximately 3500–4500 plements on IR spectroscopy, ICP-OES & May 2020 issue words long, plus figures and tables ICP-MS, and X-ray spectroscopy should Abstracts: January 10, 2020 as needed, including an abstract of be 2500–3000 words long, with up to six Manuscripts: March 2, 2020 approximately 150–200 words. Fig- figures and tables combined, and should ures and tables, along with their include an abstract of approximately 150– July 2020 issue captions, should appear at the end 200 words. We are accepting submissions Abstracts: February 7, 2020 of the manuscript, and figures also for the following issues: Manuscripts: April 13, 2020 must be sent as separate files, pref- erably in JPG, TIF, PNG, or XLS IR Spectroscopy supplement, Contact Us format. August 2019 For more information about contrib- References. Number the litera- Submission deadlines: uting to Spectroscopy, please contact ture citations in the text consecu- Abstracts: April 19, 2019 tively in order of appearance and Manuscripts: June 3, 2019 indicate them by Arabic numerals Laura Bush, Editorial Director in parentheses. Number each ref- ICP–OES & ICP–MS supplement, Spectroscopy erence separately. Group the refer- September 2019 +1.732.346.3020 ences at the end of the manuscript Submission deadlines: [email protected] in the order of their appearance in Abstracts: April 5, 2019 www.spectroscopyonline.com ◾ the text, not alphabetically. Manuscripts: June 14, 2019 52 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com PRODUCTS & RESOURCES Spectrometer Mini-spectrometer The AvaSpec-ULS4096CL-EVO Hamamatsu’s steered spectrometer from Avantes is molecular dynamics (SMD) designed with 4096 pixels, and mini-spectrometer is designed can perform measurements for high sensitivity in the down to 0.04 nm in a 200 near-infrared (NIR) region. to 1100 nm spectral range. According to the company, its According to the company, the ultra-compact (11.7×4.0×3.1 complementary metal oxide mm) C14384MA-01 is a grating semiconductor (CMOS) based type spectrometer that enables spectrometer includes AvaSoft- flexible design for applications. Basic software, a USB cable, and a manual. Avantes, Louisville, CO; Hamamatsu Corporation, www.avantes.com/products/spectrometers/starline/item/1288-avaspec- Bridgewater, NJ; uls-4096clevo www.hamamatsu.com

High-throughput screening system Temperature-controlled spectroscopy The TR-WPS automated well accessories plate measurement system The temperature controller from from Ondax, now a Coherent PIKE Technologies is designed company, is designed to to provide temperature control automatically identify and screen and responsive ramping for the polymorphic compounds and company’s heated and cooled co-crystals, or quantify degree accessories. According to the of crystallinity. According to the company, the controller is NRTL, company, the system features CE, and RoHS certified, and fea- automated calibration and tures a small footprint and user- collection, intrawell mapping, settable ramp rate or PID control. polarized light detection, and SPC and ASCII file format outputs. PIKE Technologies, Ondax, now a Coherent company, Madison, WI; Monrovia, CA; www.ondax.com www.piketech.com

UHV flanges and viewpoints Microplastics analysis technical note A new series of ultra-high A technical note from Renishaw describes vacuum (UHV) flanges and how its inVia confocal Raman microscope viewpoints from Reflex Analytical is suited for the analysis of microplastics. are designed to achieve UHV According to the company, the note performance at 10–12 cc per s explains how a combination of optical established with fluorocarbon and Raman imaging techniques can be o-ring seals and a differentially used to locate, image, and characterize pumped vacuum system. particles, even if they are sparsely According to the company, by distributed. pumping on the differential section with only a mechanical pump, UHV Renishaw Inc., pressures on the inside can be routinely achieved. West Dundee, IL; Reflex Analytical Corp., www.renishaw.com/raman Ridgewood, NJ; www.reflexusa.com

EDXRF spectrometer Sample imaging tool Rigaku’s NEX CG ParticleScout from WITec is an spectrometer imaging tool designed to identify, is designed to quantify, classify, and analyze provide qualitative particles in a sample. According and quantitative to the company, the tool enables determination of major measurements that move from and minor atomic an overview survey through elements in a variety targeted investigations of particles of sample types with grouped by attributes to the minimal standards. According to the company, the spectrometer can precise chemical characterization of individual particles. analyze 11Na to 92U nondestructively. WITec GmbH, Rigaku Corporation, Ulm, Germany; Austin, TX; www.witec.de www.rigaku.com www.spectroscopyonline.com March 2019 Spectroscopy 34(3) 53

XRF kit Raman spectrometer Amptek’s XRF kit is designed to B&W Tek’s QTRam portable help users quickly begin doing transmission Raman spectrometer elemental analysis via X-ray is designed for rapid and fluorescence. According to the nondestructive quantitative company, the kit includes the analysis. According to the company’s X-123 complete spec- company, the spectrometer is trometer with a SSD or FAST SSD operated using 21 CFR Part 11 detector, a Mini-X USB controlled compliant software, and is suitable X-ray tube, XRF-FP QA software, for blend and content uniformity a sample enclosure, and test testing of finished products, such as tablets and capsules. sample. B&W Tek, Amptek, Inc., Newark, DE; Bedford, MA; bwtek.com/products/qtram www.amptek.com

Solvent extraction system Acid purification accessories The EDGE solvent extraction system from Milestone’s Clean Chemistry CEM is designed for sample preparation. accessories are designed According to the company, the system to reduce and control the can extract up to 30 g in five min, and 12 analytical blank in ultratrace samples in one h. elemental analysis. According CEM Corporation, to the company, duoPUR and Matthews, NC; subCLEAN provide on-demand, www.cem.com in-house purification of acids, and traceCLEAN is an automated, self-contained acid steam cleaning system for trace metal analysis accessories. Milestone Inc., Shelton, CT; www.milestonesci.com/CleanChemistry

X-ray window Acid purification system The BX-1 X-ray window from The Savillex DST-4000 acid Moxtex is designed to withstand purification system is designed temperatures up to 200 °C. to convert trace metal–grade According to the company, the acid into high-purity acid in a window is suitable for applications single distillation. According to the requiring high transmission of company, the system can produce low energy X-rays, is constructed 1 L of 10 parts-per-trillion grade entirely out of low-Z materials, and acid in 12 h. The system reportedly has improved helium permeability includes an acid level sensor that performance and temperature switches the power off when the tolerance. run is completed. Moxtek, Inc., Savillex, Orem, UT; Eden Prairie, MN; www.moxtek.com www.savillex.com

Certified reference material Portable Raman spectroscopy system Certified reference material The portable StellarCASE-Raman system from Starna reportedly provides from StellarNet is designed for material qualification data, even below identification and composition analysis 200 nm. According to the using Raman spectroscopy, and is company, its TS8 reference suitable for applications in forensics, material was developed with anticounterfeiting, and enhanced Raman suitable spectral characteristics spectroscopy. According to the company, in the region of 190–230 nm, the system uses free SpectraWiz ID and the TS8 solution and a software to build and search a library for solvent blank are supplied in an any application. identically matched pair of 10 mm far UV quartz cells. StellarNet, Inc., Starna Cells, Inc., Tampa, FL; Atascadero, CA; www.StellarNet.us www.starnacells.com 54 Spectroscopy 34(3) March 2019 www.spectroscopyonline.com

Electron backscatter diffraction camera Light measurement system The Velocity EBSD The WaveGo handheld light camera from EDAX is measurement system from designed for highspeed Wave Illumination is designed electron backscatter to use Ocean Optics technology diffraction mapping. along with a user’s smart phone According to the to provide essential metrics company, the camera for quantifying light on the go. combines indexing According to the company, the speeds greater than 3000 indexed points per second, with indexing device captures the lux and success rates of 99% or better, and image resolution that provides intensity of light along with color orientation precision values of less than 0.1°. temperature, color rendering, and perceived color information. EDAX, Inc., Ocean Optics, Mahwah, NJ; Largo, FL; www.edax.com www.oceanoptics.com

Mass spectrometer Spectrometer and accessories catalog Advion’s SOLATION inductively Catalog X from Avantes reportedly provides coupled plasma mass an overview of the company’s spectrometers, spectrometer is designed light sources, and accessories. According to for multi-element analysis the company, several new products will be for environmental, clinical, introduced. The online catalog is available at biomedical, food, agriculture, https://www.avantes.com/catalog/ and geological applications. According to the company, the Avantes, Inc., mass spectrometer has a 90° Louisville, CO; quadrupole deflector and low www.avantes.com interference. Advion, Ithaca, NY; www.advion.com

Ad Index ADVERTISER PG# Alpha Resources, Inc...... 7 Amptek ...... 5 Avantes BV ...... 41, 48 B&W Tek, Inc...... 17 CEM Corporation ...... CV4 EDAX, Inc...... 47 Hamamatsu Corporation ...... 21 Milestone Inc...... 3 Moxtek, Inc...... CV3 Ocean Optics, Inc...... CV2 Ondax, Inc...... 27 PIKE Technologies ...... 35 Renishaw, Inc...... 8 Rigaku GMG ...... 13 Savillex ...... 31 Starna Cells, Inc...... 37, 39 StellarNet, Inc...... 25 Wiley ...... 15 WITec GmbH ...... 11 %;

7KHQHZKLJKWHPSHUDWXUH OLJKWHOHPHQW;UD\ZLQGRZ

LQIR#PR[WHNFRP PR[WHNFRP NEW

Never Wash Digestion Vessels Again

Safe, simple and high-throughput. Other digestion systems using disposable liners are slow, require dangerous pressures and can only digest half as many samples. The new CEM glass liner revolutionizes disposability for a fraction of the cost.

Increase your lab efficiency and lower you cost per test. • Weigh sample directly into the disposable liner without • Up to 24 samples can be digested simultaneously static interference • Dilute samples directly in the glass liner • Prepare a second set while another batch is running • Throw the liner away – No vessel washing

cem.com