DOCSLIB.ORG

Laser Raman Spectroscopy & Its Applications

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Laser Raman Spectroscopy & Its Applications NCEGR, GSI, KOLKATA Laser Raman Spectroscopy & its applications Laser Raman spectroscopy uses a monochromatic laser to interact with molecular vibrational modes in a sample, shifting the laser energy down (Stokes) or up (anti-Stokes) through inelastic scattering. It is most useful for fingerprinting chemical species of which minerals and vein forming fluids are of immediate relevance to all geological investigations and researches. Although Laser Raman spectroscopy (LRS) is most sensitive to covalent bonds with little or no natural dipole moment, as in carbon compounds, it also effectively identifies partially covalent bonds with dipole moments which characterize most known minerals. However, the system, by its basic principle, is ineffective for chemical compounds or minerals that have purely electrovalent or metallic structure. A Renishaw in Via Reflex Laser Raman Microscopies operative at the Central Petrological Laboratory, Geological Survey of India. It is a high-sensitivity system with integrated research grade microscope, enabling high-resolution confocal measurements and supports multiple lasers (540 nm and 785 nm), with automatic software switching of excitation wavelength. The other components of the spectroscope include holographic notch filter (to eliminate the elastic or Rayleigh scatter), lens systems, gratings for resolution and a charge- coupled device (CCD. The Raman spectrum collected consists of a sequence of peaks in a wave number vs intensity diagram. Each peak is associated with a different bond in the molecule. This pattern, unique to each substance, is searched against an established library database and the best correlated sample/mineral/fluid is considered the most likely match. Renishaw in Via Reflex Laser Raman Internal principle of LRS microscope Raman Spectroscopic profile for olivine Microscope Sample Preparation for LRS Laser Raman Spectroscope can easily and effectively operate on a flat surface of a mineral. Such a flat surface includes a cleavage plane or crystal face of a single crystal; a wafer, a cut and polished surface as in gemstone, a polished block of rock (sufficiently small so as to fit on the stage of the microscope) or a thin section. A thin polished section or a polished section can give excellent results. The sample should not be covered (as with a cover slip) or coated (like gold or carbon coating as done in SEM or EPMA). If the sample has already been subjected to study under SEM or EPMA and there exists a layer of coating on the sample, then for best results the coating has to be removed not simply by mechanical rubbing with organic solvent but rather more effectively by repolishing. Also carbonate samples should not be Alizarin treated as the dye has its own strong LRS signature. Procedure for LRS booking GSI officers from Regional Laboratories or from all State Units, who are interested in using the LRS, are requested to send a letter (through proper channel) to the Director, Central Petrological Laboratories, CHQ requesting a time slot. The numbers of samples and the type of samples needs to be mentioned in the letter. Also required is the e-mail and Fax contacts of the officer concerned. The allotted time slot will be sent to the officer via both e-mail and Fax. Also it is always preferred that the officer be personally present during the study of his/ her samples. The knowledge of the officer on his / her specific requirements, textural controls etc. help in both speed and accuracy of the analyses and also helps in minimizing office expenditure. NCEGR, GSI, KOLKATA Applications of LRS in Geological Investigations A. Identification of minerals: Raman Spectroscope is an easy, cost effective and non destructive application for identification of mineral phases that cannot easily be identified under microscope. The following are only a few examples of minerals that can be successfully identified with the help of LRS. i. Minerals in Bauxite and Laterite : Bauxite is a heterogeneous naturally occurring material with principal constituent minerals gibbsite (Al2O3.3H2O), boehmite (Al2O3.H2O or γ-AlO(OH)) and diaspore (α-AlO(OH)), the later having the same composition as boehmite, but is denser and harder. These are mixed with the two iron oxides goethite and haematite, the clay mineral kaolinite and small amounts of anatase TiO2. These phases are often difficult to identify separately in hand specimen or under microscope. EPMA cannot effectively separate them as they are all compositionally very similar. However, Laser Raman Spectroscopy, which depends on bond structure and is independent of mineral composition, has been shown to have distinct signatures for each of these phases and thus can be effectively used in phase identification. Garnierite group of minerals, the Ni-Mg-bearing hydrous phyllosilicates found associated with Ni- laterite, include micron scale serpentine, talc, chlorite, smectite, sepiolite etc. Each of these phases can be identified by their separate LRS signatures ii. Iron Ore minerals: The iron oxide minerals like magnetite (Fe3O4), hematite (Fe2O3), goethite(FeO(OH)), maghemite (Fe2O3, γ-Fe2O3), kenomagnetite (tetrahedral Fe3O4)are all structurally different and can be easily identified by their distinct LRS signatures. iii. Carbonate phases : Carbonates provide a wealth of information about sedimentary environments and ancient climates, as well as being important in the formation of oil reservoirs; cement industry etc. The mineralogy of ooids is usually either calcite or aragonite, which correspond to climatic greenhouse and icehouse conditions: being able to distinguish the two is therefore important in interpreting the environmental significance of a particular rock formation. Carbonate minerals such as calcite, dolomite and aragonite have similar optical properties and distinguishing them is often difficult. Alizarin Red test can successfully demarcate some phases but fail to distinguish the others. Optical techniques also require the preparation of thin sections which is time-consuming and consequently expensive. Methods such as X-ray diffraction lack spatial resolution (in most cases being restricted to examination of crushed rock or single crystals extracted from a sample) and electron microscopy techniques require polished and carbon- coated surfaces and is still not useful for calcite and aragonite as these two phases are polymorphs and therefore cannot be distinguished by compositional dataalone. Laser Raman Spectroscope has distinct and well identified set of peak positions for each of these carbonate minerals and can hence be effectively applied for mineral identification in small limestone blocks and thin sections. iv. Sulphides Sulfides (chalcopyrite, bornite, sphalerite, pyrite, marcasite, cubanite, pentlanadite, covellite,arsenopyrite) are weaker Raman scatters compared to silicates, carbonates and sulfate minerals. They have distinctive Raman bands in the ∼300–500 Δcm−1 region. Raman spectra from these mineral species are very consistent in band position and normalized band intensity albeit rather overlapping. A few sulphides, such as galena and pyrrhotite, do not exhibit a first-order Raman spectrum due to their structural symmetry and Raman spectra could not be obtained from some of the metal-excess groups of sulphides because of their many metallic characteristics. However, good quality Raman spectra are possible from most sulphides and sulphosalts. However, the sulphide phases have distinct optical properties and can be easily identified through reflected light petrography. v. Tin and Tungsten minerals The tin-tungsten minerals can be identified through petrographic study. But LRS provides an easier approach to mineral identification confirmation. The two wolframite end members ferberite (FeWO) and hubnerite (MnWO) have nearly identical structure and therefore identical peak positions in LRS. However studied signatures for scheelite NCEGR, GSI, KOLKATA (CaWO), stolzite (PbWO) and tungstite (WO8.H2O) are available and they vary sufficiently in details so as to allow LRS to identify these phases separately. Cassiterite (SnO2), stannite (Cu2FeSnS4), the rare mineral hemusite (Cu6SnMoS8) andkesterite (Cu2.04(Zn0.84Fe0.18)Sn1.01S4) have their distinct LRS signatures. However considerable degree of overlap between signatures of cernite (Cu2CdSnS4) and stannite make their distinction impossible under LRS. vi. Manganese minerals Manganese oxides, oxyhydroxides, carbonates and silicates constitute a large family of minerals. A few examples include manganosite (MnO), hausmannite (Mn2+Mn3+2O4), pyrolusite (MnO2),bixbyite (Mn2O3), ramsdellite (Mn4+O2), jacobsite (Mn2+Fe3+2O4), hollandite (Ba(Mn4+6Mn3+2)O16), manganite (Mn3+O(OH)), allactite (Mn7(AsO4)2(OH)8), birnessite (Mn-oxyhydroxide),romanechite ((Ba,H2O)2(Mn4+,Mn3+)5O10), braunite (Mn2+Mn3+6SiO12), neltnerite (CaMn3+6O8(SiO4)), rhodochrosite (MnCO3) etc.These minerals have very similar optical properties which makes it extremely difficult to separate them through reflectance and transmission microscopy. Also due to large variations in oxidation states of manganese among the oxide minerals, identification of such phases with electron microprobe may not always be reliable.However, there exists extensive LRS data on the peak shifts depending on these mineral structures. Therefore LRS is the most reasonable and cost effective approach for manganese mineral identification. vii. Manganese nodules / Polymetallic nodules Polymetallic nodules, also called manganese nodules were discovered
Load more

Recommended publications
  • A Comparison of Ultraviolet and Visible Raman Spectra of Supported Metal Oxide Catalysts
    8600 J. Phys. Chem. B 2001, 105, 8600-8606 A Comparison of Ultraviolet and Visible Raman Spectra of Supported Metal Oxide Catalysts Yek Tann Chua,† Peter C. Stair,*,† and Israel E. Wachs*,‡ Department of Chemistry, Center for Catalysis and Surface Science and Institute of EnVironmental Catalysis, Northwestern UniVersity, EVanston, Illinois 60208, and Zettlemoyer Center for Surface Studies and Department of Chemical Engineering, Lehigh UniVersity, Bethlehem, PennsylVania 18015 ReceiVed: April 11, 2001 The recent emergence of ultraviolet-wavelength-excited Raman spectroscopy as a tool for catalyst characterization has motivated the question of how UV Raman spectra compare to visible-wavelength-excited Raman spectra on the same catalyst system. Measurements of Raman spectra from five supported metal oxide systems (Al2O3-supported Cr2O3,V2O5, and MoO3 as well as TiO2-supported MoO3 and Re2O7), using visible (514.5 nm) and ultraviolet (244 nm) wavelength excitation have been compared to determine the similarities and differences in Raman spectra produced at the two wavelengths. The samples were in the form of self-supporting disks. Spectra from the oxides, both hydrated as a result of contact with ambient air and dehydrated as a result of calcination or laser-induced heating, were recorded. A combination of sample spinning and translation to produce a spiral pattern of laser beam exposure to the catalyst disk was found to be most effective in minimizing dehydration caused by laser-induced heating. Strong absorption by the samples in the ultraviolet significantly reduced the number of scatterers contributing to the Raman spectrum while producing only modest increases in the Raman scattering cross section due to resonance enhancement.
    [Show full text]
  • Atomic and Molecular Laser-Induced Breakdown Spectroscopy of Selected Pharmaceuticals
    Article Atomic and Molecular Laser-Induced Breakdown Spectroscopy of Selected Pharmaceuticals Pravin Kumar Tiwari 1,2, Nilesh Kumar Rai 3, Rohit Kumar 3, Christian G. Parigger 4 and Awadhesh Kumar Rai 2,* 1 Institute for Plasma Research, Gandhinagar, Gujarat-382428, India 2 Laser Spectroscopy Research Laboratory, Department of Physics, University of Allahabad, Prayagraj-211002, India 3 CMP Degree College, Department of Physics, University of Allahabad, Pragyagraj-211002, India 4 Physics and Astronomy Department, University of Tennessee, University of Tennessee Space Institute, Center for Laser Applications, 411 B.H. Goethert Parkway, Tullahoma, TN 37388-9700, USA * Correspondence: [email protected]; Tel.: +91-532-2460993 Received: 10 June 2019; Accepted: 10 July 2019; Published: 19 July 2019 Abstract: Laser-induced breakdown spectroscopy (LIBS) of pharmaceutical drugs that contain paracetamol was investigated in air and argon atmospheres. The characteristic neutral and ionic spectral lines of various elements and molecular signatures of CN violet and C2 Swan band systems were observed. The relative hardness of all drug samples was measured as well. Principal component analysis, a multivariate method, was applied in the data analysis for demarcation purposes of the drug samples. The CN violet and C2 Swan spectral radiances were investigated for evaluation of a possible correlation of the chemical and molecular structures of the pharmaceuticals. Complementary Raman and Fourier-transform-infrared spectroscopies were used to record the molecular spectra of the drug samples. The application of the above techniques for drug screening are important for the identification and mitigation of drugs that contain additives that may cause adverse side-effects. Keywords: paracetamol; laser-induced breakdown spectroscopy; cyanide; carbon swan bands; principal component analysis; Raman spectroscopy; Fourier-transform-infrared spectroscopy 1.
    [Show full text]
  • Laser Raman Spectroscopy As a Technique for Identification Of
    ARTICLE IN PRESS CHEMGE-15589; No of Pages 13 Chemical Geology xxx (2008) xxx–xxx Contents lists available at ScienceDirect Chemical Geology journal homepage: www.elsevier.com/locate/chemgeo Laser Raman spectroscopy as a technique for identification of seafloor hydrothermal and cold seep minerals Sheri N. White ⁎ Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, MA 02536, USA article info abstract Article history: In situ sensors capable of real-time measurements and analyses in the deep ocean are necessary to fulfill the Received 8 August 2008 potential created by the development of autonomous, deep-sea platforms such as autonomous and remotely Received in revised form 8 November 2008 operated vehicles, and cabled observatories. Laser Raman spectroscopy (a type of vibrational spectroscopy) is an Accepted 10 November 2008 optical technique that is capable of in situ molecular identification of minerals in the deep ocean. The goals of this Available online xxxx work are to determine the characteristic spectral bands and relative Raman scattering strength of hydrothermally- Editor: R.L. Rudnick and cold seep-relevant minerals, and to determine how the quality of the spectra are affected by changes in excitation wavelength and sampling optics. The information learned from this work will lead to the development Keywords: of new, smaller sea-going Raman instruments that are optimized to analyze minerals in the deep ocean. Raman spectroscopy Many minerals of interest at seafloor hydrothermal and cold seep sites are Raman active, such as elemental sulfur, Mineralogy carbonates, sulfates and sulfides. Elemental S8 sulfur is a strong Raman scatterer with dominant bands at ∼219 and Hydrothermal vents 472 Δcm−1.
    [Show full text]
  • Accessing Excited State Molecular Vibrations by Femtosecond Stimulated Raman Spectroscopy
    Accessing Excited State Molecular Vibrations by Femtosecond Stimulated Raman Spectroscopy Giovanni Batignani,y Carino Ferrante,y,z and Tullio Scopigno∗,y,z yDipartimento di Fisica, Universitá di Roma “La Sapienza", Roma, I-00185, Italy z Istituto Italiano di Tecnologia, Center for Life Nano Science @Sapienza, Roma, I-00161, Italy E-mail: [email protected] arXiv:2010.05029v1 [physics.optics] 10 Oct 2020 1 Abstract Excited-state vibrations are crucial for determining photophysical and photochem- ical properties of molecular compounds. Stimulated Raman scattering can coherently stimulate and probe molecular vibrations with optical pulses, but it is generally re- stricted to ground state properties. Working in resonance conditions, indeed, enables cross-section enhancement and selective excitation to a targeted electronic level, but is hampered by an increased signal complexity due to the presence of overlapping spectral contributions. Here, we show how detailed information on ground and excited state vi- brations can be disentangled, by exploiting the relative time delay between Raman and probe pulses to control the excited state population, combined with a diagrammatic formalism to dissect the pathways concurring to the signal generation. The proposed method is then exploited to elucidate the vibrational properties of ground and excited electronic states in the paradigmatic case of Cresyl Violet. We anticipate that the presented approach holds the potential for selective mapping the reaction coordinates pertaining to transient electronic stages implied in photo-active compounds. Graphical TOC Entry 2 Raman spectroscopy is a powerful tool to access the vibrational fingerprints of molecules or solid state compounds and it can be used to extract structural and dynamical information of the samples under investigation.
    [Show full text]
  • Combining Chemical Information from Grass Pollen in Multimodal Characterization
    ORIGINAL RESEARCH published: 31 January 2020 doi: 10.3389/fpls.2019.01788 Combining Chemical Information From Grass Pollen in Multimodal Characterization Sabrina Diehn 1,2, Boris Zimmermann 3, Valeria Tafintseva 3, Stephan Seifert 1,2, Murat Bag˘ cıog˘ lu 3, Mikael Ohlson 4, Steffen Weidner 2, Siri Fjellheim 5, Achim Kohler 3,6 and Janina Kneipp 1,2* 1 Department of Chemistry, Humboldt-Universität zu Berlin, Berlin, Germany, 2 BAM Federal Institute for Materials Research and Testing, Berlin, Germany, 3 Faculty of Science and Technology, Norwegian University of Life Sciences, Ås, Norway, 4 Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Ås, Norway, 5 Faculty of Biosciences, Norwegian University of Life Sciences, Ås, Norway, 6 Nofima AS, Ås, Norway Edited by: Lisbeth Garbrecht Thygesen, fi University of Copenhagen, The analysis of pollen chemical composition is important to many elds, including Denmark agriculture, plant physiology, ecology, allergology, and climate studies. Here, the Reviewed by: potential of a combination of different spectroscopic and spectrometric methods Wesley Toby Fraser, regarding the characterization of small biochemical differences between pollen samples Oxford Brookes University, United Kingdom was evaluated using multivariate statistical approaches. Pollen samples, collected from Åsmund Rinnan, three populations of the grass Poa alpina, were analyzed using Fourier-transform infrared University of Copenhagen, Denmark (FTIR) spectroscopy, Raman spectroscopy, surface enhanced Raman scattering (SERS), Anna De Juan, and matrix assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS). The University of Barcelona, Spain variation in the sample set can be described in a hierarchical framework comprising three *Correspondence: populations of the same grass species and four different growth conditions of the parent Janina Kneipp [email protected] plants for each of the populations.
    [Show full text]
  • Venus Elemental and Mineralogical Camera (Vemcam)
    EPSC Abstracts Vol. 13, EPSC-DPS2019-827-1, 2019 EPSC-DPS Joint Meeting 2019 c Author(s) 2019. CC Attribution 4.0 license. Venus Elemental and Mineralogical Camera (VEMCam) Samuel M. Clegg (1), Brett S. Okhuysen (1), David S. DeCroix (1), Raymond T. Newell (1), Roger C. Wiens (1), Shiv K. Sharma (2), Sylvestre Maurice (3), Ronald K. Martinez (1), Adriana Reyes-Newell (1), and Melinda D. Dyar (4), (1) Los Alamos National Laboratory, Los Alamos, NM, [email protected], (2) Hawaii Inst. of Geophysics and Planetology, Univ. of Hawaii, Honolulu, USA, (3) L'Institut de Recherche en Astrophysique et Planétologie, Toulouse France, (4) Planetary Science Inst., Tucson, AZ, USA Abstract The Venus Elemental and Mineralogical Camera The Venus Elemental and Mineralogical Camera (VEMCam) is an integrated remote LIBS and Raman (VEMCam) can make thousands of measurements instrument concept designed to operate from within within the first two hours on the surface, providing the safety of the lander. The extreme Venus surface an unprecedented description of the Venus surface. conditions requires rapid analyses and VEMCam can VEMCam is based on the ChemCam instrument on collect over 1000 chemical and mineralogical spectra the Mars Science Laboratory rover and the within the first hour. Here, we discuss the VEMCam SuperCam instrument selected for the Mars 2020 prototype calibration and analysis in which samples rover. VEMCam includes an integrated Raman and are placed in a 2 m long chamber capable of Laser-Induced Breakdown Spectroscopy (LIBS) simulating the Venus surface atmosphere. instrument capable of probing many disparate locations around the lander. VEMCam also includes 1.
    [Show full text]
  • Crystal Structure, Raman Spectroscopy and Dielectric Properties of New Semiorganic Crystals Based on 2-Methylbenzimidazole
    crystals Article Crystal Structure, Raman Spectroscopy and Dielectric Properties of New Semiorganic Crystals Based on 2-Methylbenzimidazole E. V. Balashova 1,* , F. B. Svinarev 1, A. A. Zolotarev 2, A. A. Levin 1, P. N. Brunkov 1, V. Yu. Davydov 1 , A. N. Smirnov 1 , A. V. Redkov 3, G. A. Pankova 4 and B. B. Krichevtsov 1 1 Ioffe Institute, 26 Politekhnicheskaya, St Petersburg 194021, Russian Federation; [email protected]ffe.ru (F.B.S.); [email protected]ffe.ru (A.A.L.); [email protected]ffe.ru (P.N.B.); [email protected]ffe.ru (V.Y.D.); [email protected]ffe.ru (A.N.S.); [email protected]ffe.ru (B.B.K.) 2 Institute of Earth Sciences, Saint-Petersburg State University, 7/9 Universitetskaya Nab., St Petersburg 199034, Russian Federation; [email protected] 3 Institute of Problems of Mechanical Engineering, 61 Bolshoy pr. V.O., St Petersburg 199004, Russian Federation; [email protected] 4 Institute of macromolecular compounds, 31 Bolshoy pr. V.O., St Petersburg 199004, Russian Federation; [email protected] * Correspondence: [email protected]ffe.ru Received: 27 September 2019; Accepted: 29 October 2019; Published: 31 October 2019 Abstract: New single crystals, based on 2-methylbenzimidazole (MBI), of MBI-phosphite (C16H24N4O7P2), MBI-phosphate-1 (C16H24N4O9P2), and MBI-phosphate-2 (C8H16N2O9P2) were obtained by slow evaporation method from a mixture of alcohol solution of MBI crystals and water solution of phosphorous or phosphoric acids. Crystal structures and chemical compositions were determined by single crystal X-ray diffraction (XRD) analysis and confirmed by XRD of powders and elemental analysis.
    [Show full text]
  • Article Intends to Provide a for the Necessary Virtual Electronic Brief Overview of the Differences and Transition
    ADVANCES IN RAMAN TECHNIQUES Laser requirements and advances for Raman techniques Andreas Isemann Laser Quantum GmbH, 78467 Konstanz, Germany INTRODUCTION 473 nm and 1064 nm, a narrow Raman scattering as a probe of bandwidth output of few tens of GHz vibrational transitions has made or below 1 MHz if needed within the leaps and bounds since its discovery, linewidth of vibrational transitions and various schemes based on this for high resolution, low noise (less phenomenon have been developed than 0.02%) and excellent beam with great success. quality (fundamental transversal Applications range from basic electromagnetic mode TEM00) scientific research, to medical and provides optimised performance industrial instrumentation. Some for the resolution of the Raman schemes utilise linear Raman measurement needed. scattering, whilst others take advantage The wavelength is chosen based of high peak-power fields to probe on the sample under investigation, nonlinear Raman responses. with 532 nm being commonly used This article intends to provide a for the necessary virtual electronic brief overview of the differences and transition. In the following section, benefits, together with the laser source four examples from different areas of requirements and the advancements Raman applications show the diverse in techniques enabled by recent applications of linear Raman and what developments in lasers. advances have been achieved. An example of studying a real-world LINEAR RAMAN application, the successful control of Figure 1 An example of the RR microfluidic device counting of The advent of the laser in providing a food quality using Raman spectroscopy photosynthetic microorganisms. As the cells of the model strain high-intensity coherent light source and multivariate analysis, is described Synechocystis sp.
    [Show full text]
  • Ultraviolet Raman Spectrometry Handbook of Vibrational
    Ultraviolet Raman Spectrometry Sanford A. Asher Reproduced from: Handbook of Vibrational Spectroscopy John M. Chalmers and Peter R. Griffiths (Editors) John Wiley & Sons Ltd, Chichester, 2002 Ultraviolet Raman Spectrometry Sanford A. Asher University of Pittsburgh, Pittsburgh, PA, USA 1 INTRODUCTION mid-infrared absorption measurements. Raman excitation used Hg arc emission lines and photographic detection. The Raman spectroscopy measures the magnitudes and intensi- use of the Hg arc allowed the first ultraviolet (UV) Raman ties of frequency shifts that occur because of the inelastic measurements, some of which were actually resonance scattering of light from matter.1–4 The observed shifts Raman measurements within the absorption bands of can be used to extract information on molecular structure analyte molecules. and dynamics. In addition, important information can be After 1945 the advent of relatively convenient IR instru- obtained by measuring the change in the electric field ori- mentation decreased enthusiasm for Raman spectroscopy, entation of the scattered light relative to that of the incident and it became a specialized field. Much of the work before exciting light. 1960 centered on examining molecular structure and molec- The experiment is usually performed by illuminating a ular vibration dynamics. Major advances occurred during sample with a high-intensity light beam with a well-defined this period in the theoretical understanding of Raman spec- frequency and a single linear polarization (Figure 1); the troscopy and in the resonance Raman phenomenon, where scattered light is collected over some solid angle and mea- excitation occurs within an electronic absorption band. sured to determine frequency, intensity, and polarization. The first commercial Raman instrument became available The inelastic scattering Raman phenomenon, which leads in 1953.
    [Show full text]
  • Angwcheminted, 2000, 39, 2587-2631.Pdf
    REVIEWS Femtochemistry: Atomic-Scale Dynamics of the Chemical Bond Using Ultrafast Lasers (Nobel Lecture)** Ahmed H. Zewail* Over many millennia, humankind has biological changes. For molecular dy- condensed phases, as well as in bio- thought to explore phenomena on an namics, achieving this atomic-scale res- logical systems such as proteins and ever shorter time scale. In this race olution using ultrafast lasers as strobes DNA structures. It also offers new against time, femtosecond resolution is a triumph, just as X-ray and electron possibilities for the control of reactivity (1fs 10À15 s) is the ultimate achieve- diffraction, and, more recently, STM and for structural femtochemistry and ment for studies of the fundamental and NMR spectroscopy, provided that femtobiology. This anthology gives an dynamics of the chemical bond. Ob- resolution for static molecular struc- overview of the development of the servation of the very act that brings tures. On the femtosecond time scale, field from a personal perspective, en- about chemistryÐthe making and matter wave packets (particle-type) compassing our research at Caltech breaking of bonds on their actual time can be created and their coherent and focusing on the evolution of tech- and length scalesÐis the wellspring of evolution as a single-molecule trajec- niques, concepts, and new discoveries. the field of femtochemistry, which is tory can be observed. The field began the study of molecular motions in the with simple systems of a few atoms and Keywords: femtobiology ´ femto- hitherto unobserved ephemeral transi- has reached the realm of the very chemistry ´ Nobel lecture ´ physical tion states of physical, chemical, and complex in isolated, mesoscopic, and chemistry ´ transition states 1.
    [Show full text]
  • Cobolt Lasers for Raman Spectroscopy – White Paper
    Cobolt lasers for Raman Spectroscopy – White Paper 1. Please tell us a bit about Cobolt? Cobolt AB is a Sweden-based manufacturer of high performance diode-pumped lasers and laser diodes in the UV, visible and near-infrared spectral ranges. The company’s laser products serve as key-components in advanced analytical instrumentation equipment for life science, quality control and industrial metrology applications. Cobolt is recognized on the market for providing compact, high performance, continuous wave lasers with reliable single-frequency or narrow-linewidth performance over a large range of environmental conditions. This is thanks to the company’s proprietary HTCure™ technology for advanced laser manufacturing. HTCure™ allows for robust assembly of high precision optical systems into compact, hermetically sealed packages. Cobolt was founded in 2000 and is head-quartered in Solna, Sweden, where the company’s products are developed, designed, and manufactured in a modern and ISO 9001 certified clean-room factory. The facility is specially designed for volume manufacturing of advanced lasers and laser systems. The company has direct sales offices in Sweden, Germany and the USA. Since December 2015, Cobolt AB is part of Hübner Photonics, a division of the Hübner Group. Hübner is a market leading supplier of industrial mobility solutions for the transport industry. Cobolt 04-01, 05-01 and 08-01 Series of high performance CW lasers for Raman spectroscopy 2. What are the different techniques in modern Raman Spectroscopy, and what are they used for? Thanks to rapid technology advancements in recent years, Raman Spectroscopy has become a routine, cost-efficient, and much appreciated analytical tool not only in material research applications but also for in-line process control applications in for instance pharmaceutical, food & beverage, chemical and agricultural industries.
    [Show full text]
  • Green Rust: the Simple Organizing ‘Seed’ of All Life?
    life Review Green Rust: The Simple Organizing ‘Seed’ of All Life? Michael J. Russell Planetary Chemistry and Astrobiology, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA; [email protected] Received: 6 June 2018; Accepted: 14 August 2018; Published: 27 August 2018 Abstract: Korenaga and coworkers presented evidence to suggest that the Earth’s mantle was dry and water filled the ocean to twice its present volume 4.3 billion years ago. Carbon dioxide was constantly exhaled during the mafic to ultramafic volcanic activity associated with magmatic plumes that produced the thick, dense, and relatively stable oceanic crust. In that setting, two distinct and major types of sub-marine hydrothermal vents were active: ~400 ◦C acidic springs, whose effluents bore vast quantities of iron into the ocean, and ~120 ◦C, highly alkaline, and reduced vents exhaling from the cooler, serpentinizing crust some distance from the heads of the plumes. When encountering the alkaline effluents, the iron from the plume head vents precipitated out, forming mounds likely surrounded by voluminous exhalative deposits similar to the banded iron formations known from the Archean. These mounds and the surrounding sediments, comprised micro or nano-crysts of the variable valence FeII/FeIII oxyhydroxide known as green rust. The precipitation of green rust, along with subsidiary iron sulfides and minor concentrations of nickel, cobalt, and molybdenum in the environment at the alkaline springs, may have established both the key bio-syntonic disequilibria and the means to properly make use of them—the elements needed to effect the essential inanimate-to-animate transitions that launched life.
    [Show full text]