NANOscientificVOL 17 SUMMER 2019 The Magazine for NanoScience and Technology

RESPONSIVE HYDROGEL ADVANTAGES OF HIGH COATINGS FROM PECTIN VACUUM FOR ELECTRICAL POLYSACCHARIDES EXTRACTED SCANNING PROBE FROM ORANGE PEELS MICROSCOPY p. 11 AND CACTI p. 8

UTILIZATION OF SINGLE PARTICLE ICP-MS ANALYSIS FOR NANOPARTICLE PROBING THE REDUCTION IN INTERSECTION SEMICONDUCTOR OF NANOSCIENCE FABRICATION p. 18 AND BIOLOGY p. 14 NANOSCALE VACUUM CHANNEL TRANSISTOR ON SILICON AND SILICON CARBIDE p. 15 NEUTRINO ASTROPHYSICS p. 20 The Most Accurate Atomic Force Microscope

To learn more about Park NX10 or to schedule a demo please visit www.parksystems.com/nx10 or email [email protected] A TRIBUTE TO TABLE CALVIN F. QUATE OF CONTENTS (1923–2019) NanoScientific Vol 17 Summer 2019 Figure 2: Au (60nm) NP Standard SEM image

Message from Editor 5

A Tribute to Dr. (1923-2019) 5 Keibock Lee, My Memories of Dr. Quate, Franz J. Glessibl p. 8 Editor-in-Chief Dr. Ken Nakajima Tokyo Institute of Technology: Using AFM for ISO in 7 Surface Chemistry Responsive Hydrogel Coatings From Pectin Polysaccharides Extracted 8 From Orange Peels and Cacti - Zeinab Veisi, Norma Alcantar, Ryan Toomey, Department of Chemical and Biomedical Engineering University of So. Florida Advantages of High Vacuum for Electrical Scanning Probe Microscopy 11 Jonathan Ludwig, Marco Mascaro, Umberto Celano, Wilfried Vandervorst, MESSAGE Kristof Paredis, imec, Leuven, Belgium p. 18 FROM EDITOR Probing the Intersection of NanoScience and Biology 14 Dr. Quate is best known for his role in Dr. Nathional Cady, Professor of NanoBioscience SUNY Polytechnic Welcome to our Summer Issue of NanoScientific. co-developing the atomic force Nanoscale Vacuum Channel Transistor on Silicon and Silicon Carbide 15 microscope (AFM) in the 1980’s with Dr. Jin-Woo Han, Senior Research Scientist at the Center for , With the start of summer, the natural Dr. Cady will be presenting this entire and , a NASA Ames Research Center world is buzzing with life. Baby birds lecture at the 2nd Annual NanoScientific pioneering nano metrology tool heralded as the milestone that led to decades of Park Systems Atomic Force Microscope Product Display 16 are leaving the nest and you can spot Symposium at SUNY on Nov. 19, 2019. colorful butterflies emerge from their scientific advances and garnered them Utilization of Single Particle ICP-MS Analysis for Nanoparticle Reduction 18 chrysalis after just 10 to 14 days. The This issue also offers an inside look the . The AFM established the in Semiconductor Fabrication - Lisa M. Mey-Ami, Jinjin Wang and Fuhe Li, Air p. 20 magnificence of biology in nature into the next-generation underground ability to advance scientific research Liquide Electronics - Balazs NanoAnalysis dumbfounds scientist to this day. neutrino detectors being built around exponentially and his PhD student, Dr. Sang-il Park, who brought this unique Feature Article: Neutrino Astrophysics: Seeing the Quantum Universe 20 Blazar emitting neutrinos and gamma rays. Photo Credit Ice Cube/NASA Nanoscience technology can help put the world and what they may tell us the puzzle pieces together of not just about the universe. We also share tool to the public, still manufactures his Park Systems Announces 2019 Park AFM Scholar Liliang Huang, PhD 24 Neutrino Astrophysics: Seeing the Quantum Universe the biology we can see, but also the an article on ISO Standards being innovative design today for scientists in Northwestern University Neutrinos are among the most abundant particles in the universe, a billion times more abundant than the unknown actions of particles we have developed for Surface Chemistry fields ranging from semiconductor to life Application Note: Probiotic Bacteria Topography and Nanomechanicalparticles that25 make up stars, planets and people. Neutrinos are produced in unimaginable quantities by the yet to image. Analysis and single particle inductively sciences. Properties Analysis Using Sun and stars. Could they be the dark matter that controls the fate of the universe or explain why we live in a coupled plasma-mass spectrometry universe of matter and not antimatter? World-class, multipurpose detectors designed to solve the puzzle aboutIn this issue, we feature an article about (SP ICP-MS). Our application note is “Materials Matter” Column 2 - Supramolecular Chemistry, neutrinos are26 discussed in this article along with first hand updates from two of the Physicists working in this My Memories of Dr. Quate OFI cactus who make pectin naturally focused on Hivac Advantages of High Nanomachines, and AFM - Dr. Rigoberto Advincula, Professor, area. The detector research aims to get a clearer picture of the universe, creating a new era of science: Franz J. Giessibl neutrino astrophysics. that can teach us about responsive Vacuum for Electrical Scanning Probe Macromolecular Science & Engineering Case Western Reserve University It is impossible to forget the first time I p 9 hydrogel coatings from Pectin Microscopy and in the column Materials Super-Kamiokande is the large water Cherenkov detector located in Gifu Japan.p. The 23 construction was started in met Calvin Forrest Quate. It happened Polysaccharides in research being done Matter we examine Supramolecular 1991 and the observation began on April 1st, 1996 at the Scanning Tunneling Microscopy at the Department of Chemical and Chemistry, Nanomachines, and AFM. conference at the University of Oxford in NANOScientific is published TheINSET Super-Kamiokande PHOTO ONdetector COVER: consists of a stainlessusing-steel various tank, 39.3mimaging diameter modes. and 41.4m tall, filled with Biomedical Engineering, University of NANOscientific quarterly to showcase 50,000 tons of ultra pure water. About 13,000 photoHigh-multipliers quality are Scanning installed on the tank wall. The detector is 1988, where a group of students from locatedMolybdenum at 1,000 meter disulfide underground (MoS2) in the Kamioka-mine, Hida-city, Gifu, Japan. South Florida. This research explores Lastly, we honor the legendary, Dr. Keibock Lee, Editor-in-Chief advancements in the field of Tunneling Microscopy (STM) (continued on page 6) [email protected] is two-dimensional (2D) pectin polysaccharides, complex and Calvin Quate with a tribute from one nanoscience and technology One of the purposes of the Super-Kamiokande experimenttopography is to reveal of a athe multi-layer neutrino properties through the Debbie West, Content Editor across a wide range of layered material widely used observation of solar neutrinos, atmospheric neutrinosMoS2 and sample man-made acquired neutrinos. in In high 1998, from the observation of structurally diverse group of natural of his colleagues, his contribution to [email protected] multidisciplinary areas of atmosphericfor various neutrinos research we discovered field the neutrino oscillations which neutrinos are changing their types in flight. In vacuum without necessitating polymers that could lead towards nanoscience is far reaching and his love Byong Kim, Technical Director research. The publication is 2001,both solar industry neutrino oscillations and academy were discovered by the observation of solar neutrinos. In 2011, the third neutrino offered free to anyone who works oscillation mode was discovered by man-made nespecialutrino observation. sample prep/handling replacing petroleum-based polymers of science and new discoveries had a Debbie Bishop, Art Director for advanced semiconductor in the field of nanotechnology, using Park NX-Hivac SPM is with sustainable alternatives. worldwide impact on so many and he Richard Oettinger, Marketing Manager industry applications. nanoscience, microscopy and shown with high resolution was a true inspiration. other related fields of study and The characterization and Publisher & Corporate Officers visualization of islands and manufacturing. exploration of electrical and We also have an abstract from Park Systems Corporation grain boundaries in the mechanical properties of 2D Prof. Cady, who obtained his Ph.D. Sang-il Park, Chief Executive Officer We would enjoy hearing from topography image. in Microbiology and is currently a Karen Cho, VP of Finance material are one of the most you, our readers. Send your critical points in materials professor of nanobioscience in the Keibock Lee Keibock Lee, President research or story ideas to Editor-in-Chief Park Systems, Inc. [email protected] research field. The scanning College of Nanoscale Science at SUNY Franz J. Giessibl currently works at the 3040 Olcott Street probe microscope (SPM) allows Polytechnic Institute, called “Probing Institute of Experimental and Applied Physics, Santa Clara, CA 95054 To view all of our articles, please to evaluate 2D materials in the Intersection of Nanotechnology and University Regensburg where he does research [email protected] visit our web site at multidirectional viewpoints Biology”. in Condensed Matter Physics, Experimental www.parkystems.com www.nanoscientific.org Physics, Electronics and Mechanics.

4 NANOscientific www.nanoscientific.org NANOscientific 5 wore red sweatshirts He asked about the project I was working joint papers, writing in an email in 2006 that showed the face of a man in raster on, and immediately offered that I call "Wonderful stuff Franz. Thanks for including lines, with "the face of things to come" him "Cal". After Binnig had applied for a me. I have gotten a lot of mileage from written on them. patent for the atomic force microscope the article by showing it to people who ISO FOR SURFACE CHEMICAL (AFM) in 1985, an extension of STM that assumed that I was over the hill“. should also be able to image insulators at ANALYSIS USING SCANNING very high resolution, Gerd Binnig, Calvin The engineer in Cal always loved F. Quate and Christoph Gerber set out to applications - I remember I once met build an AFM and published a seminal Cal on the weekend in Fry’s Electronics, PROBE MICROSCOPY paper in Physical Review Letters (2) about it. a large electronic outlet, where he was Cal realized that the cantilever of AFM that looking at the new gadgets that had made probes the forces between its tip and the it from laboratory to market to be inspired An example for the tire industry is to Scope: This international standard DR. KEN NAKAJIMA add carbon nanoparticles for durability describes a procedure for the sample was essential to the performance by them and spur his imagination. The PROFESSOR IN THE SCHOOL OF and then measure the nanometer determination of elastic modulus for of the new microscope and set up a visionary in Cal was a man who looked for MATERIALS AND CHEMICAL TECHNOLOGY, particles distribution and intervention. compliant materials using atomic force program to design micromachined progress in many places. He hired students TOKYO INSTITUTE OF TECHNOLOGY “Industry executives need qualitative microscope (AFM). Force-distance curves cantilevers made from SiO , Si N and from all over the world and interacted The Nakajima Laboratory's expertise is 2 3 4 measurements,” adds Dr. Najajima. His on the surface of compliant materials later Si in the Stanford micromachining intensively with physicists, engineers, polymer nanomechanics, in other words, group consults and corroborates with are measured and the analysis uses a facilities. He supplied these cantilevers chemists, mathematicians and computer investigating nano-scale structures and industry and many of his students find two-point method based on Johnson- (4) to our Munich IBM group that was started scientists. In his spare time, he loved to properties of polymeric materials, by industry jobs when they leave academics. Kendall Roberts (JKR) theory[1,2]. This by Gerd Binnig and Christoph Gerber in hike in nature with his students. which it connects knowledge in nano to International Standard is applicable to I had just started to work on my PhD 1987 were I became a member in 1988. macroscopic world. "No swallow written in Dr. Nakajima works with many AFM the compliant materials of elastic moduli thesis with Gerd Binnig, who won the 1986 After having obtained a PhD with Gerd, I Cal passed away in his home in Menlo textbooks" is our motto. The lab is currently (3) manufacturers and sees a solution ranging from 100 kPa to 1 GPa. The Nobel Prize in Physics together with Heini joined Park Scientific Instruments (PSI), Park on July 6 2019 . His love for science involved in several national projects such offered by every manufacturer based on spatial resolution is dependent on the Rohrer for the invention of the scanning a company that was founded by Cal’s and engineering radiated to many of his as CAO SIP, CAO ImPACT, that company’s product and strengths. contact radius between an AFM probe tunneling microscope (STM). STM was former student Sang-il Park with Calvin students and coworkers, and his gentle JST CREST. introduced at a time where personal Quate on the board of directors. While AFM and humble ways made it natural for them When specifically asked about Park and the surface and is typically 10 nm. Systems AFM, he replied, “Park Systems computers and computer graphics were at that time was mostly used in ambient to return this respect and admiration. At Tokyo Institute of Technology, Dr. big advantage is in measurement accuracy Atomic force microscope (AFM) is a rudimentary at best. Accordingly, images conditions to image all types of samples When the Kavli Prize for Nanoscience was Ken Nakajima is working with other because their AFM’s biggest feature family of scanning probe microscope were recorded trace by trace on chart on the nanometer scale, achieving atomic awarded to Gerd Binnig, Christoph Gerber institutions to create a new ISO Standard is having an accurate piezoelectric XY (SPM) used to image surfaces by recorders and a face was printed on the resolution in vacuum similar to STM and Calvin Quate in 2016, about a dozen for using SPM for surface chemical scanner, Park’s XY scanner is wonderful mechanically scanning a probe over sweatshirts in that style. I wondered, "Who was still not possible. My project at PSI of his former students and associates analysis. This ISO is important to the and they are also strong in the the surface. In AFM, a surface force is this man, pictured on these shirts?“ was to design a room temperature UHV joined the ceremony in Oslo - a quarter rubber tire industry, where Dr. Nakajima semiconductor industry.” is monitored as the deflection of a The face showed Calvin Forrest Quate, microscope that utilized the piezoresistive of a century after their graduation. Calvin works closely with all the leading compliant cantilever, which has a probe Edward Leland professor for Electrical cantilevers that were invented in Cal’s Quate received multiple other honors, manufacturers. He has pioneered methods at its free end in order to interact with Engineering and Applied Physics at group. This microscope achieved atomic including the IEEE Medal of Honor, the for Nanorheological Mapping of Rubbers Summary of the ISO currently underway surfaces. AFM can provide amongst Stanford University, born Dec 7, 1923. resolution on the reconstructed surface United States National Medal of Science, by AFM and AFM-based Nanomechanics ISO (the International Organization other data: topographic, mechanical Professor Quate had been working on of Si(111)-(7x7), a feat that was important the Joseph F. Keithley Award For Advances rubber-filled interfaces. “We need to for Standardization) is a worldwide and chemical information about a microwave technology and electron because atomic imaging of this surface by in Measurement Science and others know the distribution and intervention federation of national standards bodies surface depending on the mode of beam interactions at Bell Labs, and was STM introduced this instrument into the and was a member of both the National of nanometer particles,” comments Dr. (ISO member bodies). The work of operation and the property of the probe a vice president and director of research toolbox of the thriving field of surface Academy of Sciences and the National Nakajima. “These properties can only be preparing International Standards tip. Accurate force measurements and at Sandia Labs before joining Stanford. science. Cal frequently visited PSI - he had Academy of Engineering. measured using AFM.” is normally carried out through ISO At Stanford, he did pioneering work in his way of looking deep into your eyes technical committees. Each member sample deformation measurements are needed for a wide variety of applications, microwave acoustics and introduced the expressing his confidence in students and His former students became officers The importance of mechanical property body interested in a subject for which a especially to determine the elastic acoustic microscope. At the age of almost coworkers by gently saying, "you can do it“. and researchers in large Silicon Valley mapping is evident by the top five technical committee has been established moduli of compliant materials such sixty, he learned about vacuum tunneling corporations such as IBM, KLA-Tencor tire manufacturers who work with Dr. has the right to be represented on that as organics and polymers at surfaces. and its potential use for microscopy on a He also supported me in publishing the and others. One of his former students Nakajima’s group at the Dept. of Chemical committee. International organizations, For quantitative force measurements, flight to Europe. Professor Quate was on successful imaging of Si(111)-(7x7) in founded a leading AFM company, one Science and Engineering at the University governmental and non-governmental, the adequate selection of contact his way to a conference in London and Science in 1995. During a visit of Cal in my managed the US research station on of Tokyo. in liaison with ISO, also take part in extended his itinerary by a visit to the IBM new affiliation at Jochen Mannharts chair the South Pole, some others became the work. ISO collaborates closely with mechanics used in calculating the elastic modulus and the appropriate Research Laboratory in Zurich to learn at the University of Augsburg (Germany), professors at distinguished universities The new ISO Standardization will have the International Electrotechnical calculation procedure are required. about scanning tunneling microscopy Cal suggested to study graphite with around the world. a significant impact on the rubber tire Commission (IEC) on all matters of (1) This International Standard describes first hand . Calvin Quate ended his talk our newly built low temperature AFM. and other industries as they look at the electrotechnical standardization. a procedure for the determination of at the 1988 conference on STM discussing Graphite was widely used in ambient STM Cal is deeply missed, but he left a rich value-added proposition and standards elastic moduli for compliant materials the many possibilities of scanning probe and allowed even beginners to achieve legacy. for integrating nanoparticles into their Surface chemical analysis using AFM. Force-distance curves microscopy (SPM). I introduced myself atomic resolution easily, while exposing products. The tire industry specifically is Scanning probe microscopy — Procedure 1. Vacuum Tunneling: A New Technique for Microscopy, Calvin F. Quate, measured on the surfaces of compliant and asked whether his ending about the a few miracles such as giant corrugations Physics Today 39(8), 26 (1986); https://doi.org/10.1063/1.881071 very interested in the interfacial region for the determination of elastic moduli 2. Atomic Force Microscope, G. Binnig, C.F. Quate, Ch. Gerber, Phys. Rev. materials are used for the calculation perspective of SPM related to a magic and the appearance of only one of the two Lett. 56, 930 (1986). because engineers know that the interface for compliant materials using atomic 3. Calvin F. Quate, inventor of advanced microscopes, dies at 95, Andrew force microscope and the two-point based on Johnson-Kendall-Roberts chestful of endless possibilities, which he atoms per unit cell in the STM images. Cal Myers,https://news.stanford.edu/2019/07/10/calvin-f-quate-inventor- of the nanoparticles and rubber is advanced-microscopes-dies-95/ JKR method. (JKR) two-point method. acknowledged with a witting smile. was enthusiastically contributing to the 4.Photo by Thomas Albrecht, linescan rendering by Sang-il Park. important.

6 NANOscientific www.nano-scientific.org www.nanoscientific.org NANOscientific 7 FEATURE ARTICLE The pectin polysaccharides extracted from both orange peels and OFI cacti have a high molecular weight and are capable of holding high volumes of water within the polysaccharide matrices, rendering hydrogels with a RESPONSIVE HYDROGEL multitude applications. However, the pectin from the orange peels is highly COATINGS FROM PECTIN esterified with a degree of esterification near 70%, whereas the pectin from OFI cactus has a much lower degree of POLYSACCHARIDES esterification (near 25 %).

EXTRACTED FROM Coatings of each type of pectinpolysaccharide were fabricated by first spin-coating the pectin solution ORANGE PEELS AND CACTI Figure 1. Collapse of Poly(NIPAAm) hydrogel as onto a solid surface followed by temperature is increased above 32 ˚C exposure to a calcium chloride (CaCl2)/ ethanol solution. Ethanol, a poor solvent for pectin, prevents dissolution of the coating while simultaneously allowing CaCl diffusion in order ZEINAB VEISI, NORMA ALCANTAR, AND RYAN TOOMEY 2 to establish Ca2+ bridges between DEPARTMENT OF CHEMICAL AND BIOMEDICAL ENGINEERING, carboxyl groups to cross-link the pectin coating. The underlying mechanism UNIVERSITY OF SOUTH FLORIDA, TAMPA, FL 33620 Figure 2. (a) Schematic of the cross-linked pectin coating; (b) ATR-FTIR spectra of the is understood by the well-known pectin coatings based on orange peels and OFI Cactus; (c) Swelling profiles of the ‘egg-box’ model, which describes Hydrogel coatings are a class of For example, as shown in Figure 1, stimuli-sensitive hydrogels. Pectin the formation of networks through pectin coatings as a function of temperature. tethered or spatially-confined hydrogels of poly(NIPAAm) in water is a heteropolysaccharide extracted associations between Ca2+ and acidic polymers capable of absorbing undergo a hydrophilic/hydrophobic from cell walls and intercellular regions of the pectin.16-19 significant amounts of water. They transition at roughly 32oC.5-6 regions of plants or their fruits are further divided into so-called (such as cactus mucilage or orange Figure 2(a) shows a schematic of stimuli-responsive hydrogels, These types of polyemrstypically peels7-9) functioning as the hydrating the cross-linked pectin coating and which are materials that imbibe or comprise moieties that have both component of the cellulosic chemical composition. Figure 2(b) expel water on demand allowing hydrophobic and hydrophilic network.10-11 In general, the structure shows the attenuated total reflection in situ control of properties and character, such that a small change in is mostly composed of D-galacturonic Fourier transform infrared spectroscopy the capacity to generate work. The the environmental conditions cause acid residues linked by α-1,4- (ATR-FTIR) spectra of the two types of “stimuli-responsive” designation a change in the balance between glycosidic bonds, which are often pectin coatings (extracted from the originates from the ability of the these two characters, either favoring interrupted with different sugars such orange peels and OFI cactus). The hydrogel to sense its physical and the swollen “hydrophilic” state or as rhamnose, arabinans, galactose, two most relevant peaks with respect chemical environment, process the collapsed “hydrophobic” state. xylose, etc. The carboxyl group to the degree of esterification are data, and respond, often with strong At low temperatures, solubility of associated with the D-galacturonic centered at approximately 1610 cm-1 amplification of the input signal. the macromolecule is engendered acid residue exists in two primary (corresponding to the carboxylate, or Thin films of stimuli-responsive through favorable mixing of the forms: The carboxylate salt and the –COO- vibration of the non-esterified polymers have been demonstrated hydrophilic moieties and water. As neutral ester form.12-15 Depending galacturonic acid residues) and 1740 in technologies that benefit temperature is increased, a point is on the pectin source and extraction esterified galacturonic acid residues.20 swells and releases the attached cells. cm-1 (corresponding to the carboxyl- from reversible modulation of reached where mixing can no longer technique, pectinscan either have The transition is stronger in the orange After 60 min of incubation at 20 ˚C, the ester, –COOR, vibration of the esterified surface properties, including drug stabilize hydrophobic interactions and a low esterified content (LE, <50 peel pectin due to the higher degree of majority of the cells are detached from galacturonic acid residues). The bands delivery,separations, tissue cultures, the polymer phase-separates from % esterification) or high esterified esterification, providing a mechanism the coating. associated with the esterified residues and chromatography.1-4 solution, leading to a strong collapse content (HE, >50% esterification). to tune the transition depending solely in OFI cactus pectin are less distinct in the volume of the hydrogel. This opens up non-synthetic routes on degree of esterification. In conclusion, pectin extracted from than the orange peel pectin indicating Most commonly, such stimuli- to tune the response of the pectin natural sources shows promise a lower degree of esterification. The responsive hydrogels are derived from With a growing demand towards coatings based solely on the source As a demonstration of the thermal as responsive hydrogel coatings, resultant swelling profiles for 100 nm petroleum-based monomersthat replacing petroleum-based polymers and method of extraction. response of the pectin coatings, which has the potential to replace thick films are shown in Figure 2(c). undergo changes in solubility with sustainable alternatives, we have Figure 3 shows the ability of the orange petroleum-derived materials. The The degree of swelling is defined as with either pH or temperature. explored pectin polysaccharidesto To illustrate this point, pectin was peel pectin coating to culture and degree of esterification furthermore the swollen thickness divided by the Poly(N-isopropylacrylamide), or mimic such properties. Pectin extracted from two sources: orange release NIH3T3 mouse embryonic allows control over the response, dry thickness. Interestingly, both types poly(NIPAAm), is a well-known lower polysaccharides are a complex and peels and Opuntia ficus-indica(OFI) fibroblast cells. When cultured at 37 which opens up avenues to control of pectin have a prominent deswelling critical solution temperature (LCST) structurally diverse group of natural cacti. The OFI cactus (commonly ˚C, the coating is collapsed providing properties of the coating solely transition as temperature is increased polymer that experiences a sharp polymers that possess hydrophilic referred to as Nopal or prickly pear) is an adhesive surface for cells to attach through the source and type of above 30 ˚C, which we have shown phase transition when subjected to and hydrophobic functionality, which grown in semi-arid and arid regions as and spread. Upon lowering the culture extraction process without having to to be driven by the dehydration of the small perturbations in external stimuli. could have significant potential as a food source. temperature to 20 ˚C, the coating resort to additional synthesis.

8 NANOscientific www.nano-scientific.org www.nanoscientific.org NANOscientific 9 APPLICATION (10) Thakur, B. R.; Singh, R. K.; NOTE Handa, A. K.; Rao, M., Chemistry and ADVANTAGES OF HIGH Uses of Pectin—a Review. Critical Reviews in Food Science & Nutrition VACUUM FOR ELECTRICAL 1997,37, 47-73. (11) Burton, R. A.; Gidley, M. J.; Fincher, G. B., Heterogeneity in the SCANNING PROBE Chemistry, Structure and Function of Plant Cell Walls. Nature Chemical Biology 2010,6, 724-732. MICROSCOPY (12) Ridley, B. L.; O'Neill,

M. A.; Mohnen, D., Pectins: 1,2, 1,2, 1 1,2, 1 Structure, Biosynthesis, and Jonathan Ludwig Marco Mascaro Umberto Celano , Wilfried Vandervorst Kristof Paredis 1. IMEC, Oligogalacturonide-Related Leuven, Belgium 2. Department of Physics and Astronomy, University of Leuven, Leuven, Belgium Signaling. Phytochemistry 2001,57, 929-967. Introduction (13) Willats, W. G.; Knox, J. P.; The discovery of graphene as the Mikkelsen, J. D., Pectin: New Insights prototype of a new class of materials in into an Old Polymer Are Starting 2004 has led to an enormous scientific to Gel. Trends in Food Science & interest in two-dimensional (2D) layered Technology 2006,17, 97-104. materials.1 Since then, a wide variety (14) Yapo, B. M., Pectic Substances: of 2D materials have been synthesized From Simple Pectic Polysaccharides and explored.2–6 Among them, the family to Complex Pectins—a New of transition metal dichalcogenides Hypothetical Model. Carbohydrate (TMDs) has attracted specific interest Polymers 2011,86, 373-385. from the semiconductor industry (15) Mohnen, D., Pectin Structure owing to an inherent band gap, a small and Biosynthesis. Current opinion in dielectric constant, high mobilities, plant biology 2008,11, 266-277. and ultrathinmaterials, which are Figure 3. A pectin coating is adhesive to cells in the collapsed state (37 ˚C) and repulsive (16) Powell, D.; Morris, E.; Gidley, heralded as promising candidates for Figure 1: (a-c) AFM topography images of the samples studied. (d) Schematic of C-AFM Figuresetup 1:used (a-c) AFMto measure topography multilayer images ofMoS the 2samples on a sapphire.studied. (d) (e) Schematic Cartoon of showingC-AFM setup how the scaling logic technology beyond the to cells in the swollen state (20 ˚C), functioning as an on-off tissue culture platform. M.; Rees, D., Conformations and usedcantilever to measure twists multilayer as it scans MoS 2over on a asapphire. high friction (e) Cartoon region. showing (f) Cross how thesection cantilever of topography twists Interactions of Pectins: Ii. Influence 5nm node. However, the integration of ascorresp it scansonding over ato high black friction line region.in (b) showing(f) Cross section0.6nm ofstep topography at the MoS corresponding2 island edge to blackand 0.2nmline References in (b) showing 0.6nm step at the MoS island edge and 0.2nm step at the sapphire terrace. All of Residue Sequence on Chain such materials in a 300mm compatible step at the sapphire terrace. All images2 are plotted in Gwyddion. Scale bar is 500nm. Association in Calcium Pectate manufacturing environment still images are plotted in Gwyddion. Scale bar is 500nm. (1) Hoffman, A. S., Environmentally (5) Schild, H. G., Poly Atomic force microscopy (AFM) images of all the samples measured are shown in figure 1.In Gels. Journal of molecular biology faces many challenges. As the praised total, three samples were measured with layer thicknesses of 1-2 layers, 3-4 layers, and one Sensitive Polymers and Hydrogels - (N-Isopropylacrylamide) - Experiment, properties have mostly been observed All measurements are performed on the An example of the sample structure 1982,155, 517-531. as-grown,with pyramid un-transferred structures, referredMoS /sapphire. to here as multifor-layer theed 3-4 MoS layer2. Thesample 1-2 islayer shown sample in Smart Biomaterials. Mrs Bull 1991,16, Theory and Application. Progress in (17) Walkinshaw, M.; Arnott, S., very locally, in flakes or single grains, consists of a completely closed2 monolayer MoS2 film with additional monolayer islands Theforming room on temperature top. These mobilitymonolayer for islands constitutefigure the 1(d).beginning Here, eachof the green growth layer of the 42-46. Polymer Science 1992,17, 163-249. Conformations and Interactions the controlled growth, transfer and devicessecond madelayer andfrom can the be same identified material as the light-coloredrepresents regions one in layerthe topography of MoS2. In image . (2) Huber, D. L.; Manginell, R. P.; (6) Shibayama, M.; Tanaka, T., processing of high quality TMD layers 2 of Pectins: Ii. Models for Junction areSimilarly, found tothe be 3 -up4 layerto µm sample ~ 30 cm consist/Vs, s of a completelyaddition clo tosed MoS tri -islands,layer MoS we2 alsofilm seewith Samara, M. A.; Kim, B. I.; Bunker, B. C., Volume Phase-Transition and Related remain a key hurdle. 2 Zones in Pectinic Acid and Calcium withadditional higher monolayer average mobilitiesislands. An for example thicker of the samplediagonal structure lines for running the 3-4 acrosslayer sample each is Programmed Adsorption and Release Phenomena of Polymer Gels. Adv Polym shown in figure 1(d). Here, each green layer represents one layer of MoS2 Pectate Gels. Journal of Molecular samples.12 sample. These are terraces. In fromaddition the to of Proteins in a Microfluidic Device. Scanning probe microscopy, as an MoS2 islands, we also see diagonal lines running across each sample. These are terraces Sci 1993,109, 1-62. Biology 1981,153, 1075-1085. sapphire substrate, which can be seen Science 2003,301, 352-354. (7) Voragen, A. G.; Coenen, G.-J.; inherent high resolution 2D technique, is from the sapphire substrate, which can be seen through the 2D film. The sapphire terraces (18) Axelos, M.; Thibault, J., The Atomiccan be forceunambiguously microscopy distinguished (AFM) images from MoS2 layersthrough by the the step 2D height, film. The0.2nm sapphire for c-plane (3) Kikuchi, A.; Okano, T., Intelligent Verhoef, R. P.; Schols, H. A., Pectin, a a powerful enabler for investigating the Chemistry of Low-Methoxyl Pectin ofsapphires all the samples. 0.6nm for measured a monolayer are shownMoS2 step, as canterraces be seen canfrom be the unambiguously cross section in figure morphological and electrical properties 13,14 Thermoresponsive Polymeric Versatile Polysaccharide Present in Plant Gelation. The chemistry and in1 figure(f). 1.In Th etotal, multi three-layer samples sample werediffers from the distinguishedother two in that from the MoS MoS layers2 surface by is of TMDs. In this technical note, we will characterized by 3D pyramid-like structures. These pyramids sit on a completely2 closed tri- Stationary Phases for Aqueous Cell Walls. Structural Chemistry 2009,20, technology of pectin 1991,6, 109- measured with layer thicknesses of the step height, 0.2nm for c-plane Chromatography of Biological 263. illustrate the advantages of high vacuum layer, and their formation is due to a change in the growth mechanism from layer-by-layer to 108. for electrical measurements utilizing the 1-23D layers,with increasing 3-4 layers, layer and thickness. one with Details of the growthsapphires. can be found0.6nm in for ref a.12 monolayer. Compounds. Progress In Polymer (8) Goycoolea, F. M.; Cárdenas, A., pyramid structures, referred to here MoS step, as can be seen from the (19) Grant, G. T.; Morris, E. R.; capabilities of the Park NX-Hivacatomic 2 Science 2002,27, 1165. Pectins from Opuntia Spp.: A Short as multi-layered MoS . The 1-2 layer cross section in figure 1 (f).13,14 The Rees, D. A.; Smith, P. J.; Thom, D., force microscopy system (Park Systems) Conducting Scanning2 Probe Microscopy (4) Kushida, A.; Yamato, M.; Konno, Review. Journal of the Professional Biological Interactions between using MoS as an example material. sample consists of a completely closed multi-layer sample differs from the C.; Kikuchi, A.; Sakurai, Y.; Okano, T., Association for Cactus Development 2 monolayerHere we employMoS film two with conducting additional scanning probeother microscopy two in that (SPM) the MoS techniques surface to Polysaccharides and Divalent 2 2 Decrease in Culture Temperature 2003,5, 17-29. monolayercharacterize islands the electronic forming propertieson top. of MoS2: Conductiis characterizedve Atomic byForce 3D pyramid-likeMicroscopy ( C- Cations: The Egg-Box Model. FEBS Investigation: Material and Methods AFM) and Scanning Tunneling Microscopy (STM). In C-AFM, the cantilever is in contact with These monolayer islands constitute the structures. These pyramids sit on Releases Monolayer Endothelial (9) Maran, J. P.; Sivakumar, V.; letters 1973,32, 195-198. MoS the surface of the material and we simultaneously record topography and current. To 2 beginning of the growth of the second a completely closed tri-layer, and Cell Sheets Together with Deposited Thirugnanasambandham, K.; Sridhar, (20) Veisi, Z.; Gallant, N. D.; Alcantar, measure the electrical current, a bias is applied to the sample chuck and current is Fibronectin Matrix from Temperature- R., Optimization of Microwave Assisted layermeasur anded can by anbe externalidentified current as the amplifier light- connectedtheir to a formation conducting is AFM due toprobe. a change Electrical in N. A.; Toomey, R. G., Responsive A series of MoS2 samples with varying Responsive Culture Surfaces. Journal of Extraction of Pectin from Orange Peel. layer thickness were grown by metal coloredcontact toregions the material in the topographyis made by applying image. silver paintthe togrowth the top mechanism and sides offrom the layer-material. Coatings from Naturally Occurring We use commercially available Pt-Ir coated probes, such as PPP-CONTSCPt or PPP- Biomedical Materials Research 1999,45, Carbohydrate polymers 2013,97, 703- organic chemical vapor deposition (MO- Similarly, the 3-4 layer sample consists of by-layer to 3D with increasing layer Pectin Polysaccharides. Colloid aNCSTPt, completely with closednominal tri-layer spring MoSconstants film in the rangethickness. of 0.2 to Details 7 N/m. of Sincethe growth C-AFM can is a 355-362. 709. CVD) on sapphire substrates. 2 Surface B 2019,176, 387-393. withcontact additional-based AFM monolayer technique, islands. it also allows the lateralbe found force into ref.12.be recorded along with the other C-AFM channels. Lateral force microscopy (LFM) measures the lateral deflection of

10 NANOscientific www.nano-scientific.org www.nanoscientific.org NANOscientific 11

Despite the fact thatthe C-AFM probe is in direct contact with the material, the low force appliedresults in no removal ofMoS2 material over the repeated scans. Figure 3 shows the topography image from the same sample after 5 scans in HV at ~30nN force with a probe with nominal spring constant at ~7N/m.

the laser on the PSD due to torsion, or twisting, of the cantilever as it scans across the surface, as depicted in figure 1(e).The difference between the forward and reverse LFM images is proportional to the friction of the materialist differs from C-AFM in that a Figure 3: Topography image of a3-4 layer MoS2 (a) initially and (b) after 5 successive scans conductive wire, cut Pt-Ir in our case, is used to measure the tunneling current between the probe and the sample when the probe is a few angstroms above the surface. STM can be at 0.1V set point using a PPP-NCSTPt probe with spring constant of ~7N/m. Scale bar is performed by either keeping the height constant and recording the current (referred to as 50nm. constant height mode) or using the feedback to keep the current level constant and recording the height (constant current mode). In constant current mode, the height image contains both topographic and electronic information. C-AFM + LFM for Grain Boundary Analysis

C-AFM in Air vs High Vacuum When imaging with a low spring constant probe, such as PPP-CONTSCPtwith nominal spring constant of 0.2N/m, we can acquire frictional data simultaneously with C-AFM, In order to demonstrate the importance of the water layer on the surface on 2D materials, we allowing for correlation between topographic, electrical, and material properties. Figure 3 performed C-AFM on the same MoS2 sample in air and high vacuum (HV), figure 2 (a-b) and st (c-d), respectively. While the topography images for the scan in airand HVare quite similar, shows the height, friction, and current images from a 1-2 layer MoS2 sample. The 1 layer the C-AFM images differ considerably. Most notably, the measured current increases by and 2nd layer regions are labeled as 1Ly and 2Ly, respectively, in figure 3(a). The friction at three orders of magnitude in HV. The average current level in air is 1.4nA at 5V bias, while grain boundaries is higher than the pristine regions, so that they show up as dark lines in the in HV it is 1.1µA. The increase in current level is due to the removal of the thin water layer friction. By comparing the current and friction, we can see that the dark lines in the friction that is always present on the surface of the sample in air. This water layer is particularly image match the dark lines in the current. However, the current image shows additional problematic for MoS2 as it p-dopes the material, effectively turning it off electrically. From features due to the influence of the substrate on the local conductivity of the 2D film. electrical transport of similar CVD grown MoS2 devices, the on state current is severely degraded and mobility decreases by 40% after exposure to DI water for two hours.15 Conducting Scanning Probe Microscopy

Here we employ two conducting scanning probe microscopy (SPM) techniques to characterize the electronic properties of MoS2: Conductive Atomic Force Microscopy (C-AFM) and Scanning Tunneling Microscopy (STM). In C-AFM, the cantilever is in contact with the surface of the material and we simultaneously record topography and current. To measure the electrical Figure 4: (a) Topography, (b) Friction, and (c) current acquired simultaneously on an 1-2 layer as-grown MoS2/sapphire sample. The layer thickness current, a bias is applied to the sample Figureof each region 4 :is indicated(a) Topography, in (a). Scale bar is 200nm.(b) Friction, and (c) current acquired simultaneously on an 1-2 chuck and current is measured by an layer as-grown MoS2/sapphire sample. The layer thickness of each region is indicated in (a). external current amplifier connected to a ScaleC-AFM + LFMbar foris Grain200nm. Boundary systems and special sample prep/ versatile imaging and measurement tool, conducting AFM probe. Electrical contact Analysis handling. Figure 4 shows a 500nm allows us to evaluate 2D materials in to the material is made by applying silver scan of the multi-layer MoS2 sample multidirectional viewpoints using various paint to the top and sides of the material. When imaging with a low spring constant imaged in constant current mode, imaging modes.This study underlines the We use commercially available Pt-Ir Scanningprobe, such as PPP-CONTSCPtwithTunneling Microscopy with I seton=0.5nA MoS and2 V bias=1V. Since STM improving strategy of material analysis. coated probes, such as PPP-CONTSCPt nominal spring constant of 0.2N/m, we gives a convolution of topography with Moreover, these results emphasize or PPP-NCSTPt, with nominal spring can acquire frictional data simultaneously electronic structure, we see both islands the importance of multidirectional constants in the range of 0.2 to 7 N/m. Withwith C-AFM, the allowing ParkNX for correlation-Hivac, we wereand grainable boundaries to also in acquire the height image.high qualityand multichannel STM images analysis on without 2D the Since C-AFM is a contact-based AFMFigure 2: C-FigureAFM 2:from C-AFM thefrom thesame same 3 3-4-4 MoS MoS sample2 sample showing showingthe increased the current increased level and current level and Despite the fact thatthe C-AFM probe is2 in direct contact with the material, the low force needbetween fortopographic, complicated electrical, andUHV systems and special sample prep/handling.materials, including Figure the transition 4 shows metal a technique, it also allows the lateralsensitivity force undersensitivity high under vacuum. high vacuum. (a) (a) Topography Topography and and(b) current (b) imagescurrent in air images at 5V bias. in (c) air at 5V bias. (c) material properties. Figure 3 shows the Conclusion dichalcogenides that are of high interest appliedresults in no removal ofMoS2 material over the repeated scans. Figure 3 shows the 500nm scan of the multi-layer MoS2 sample imaged in constant current mode, with to be recorded along with the otherTopography Topographyand (d) current and (d) current images images taken taken immediatelyimmediately after afterpumping pumping to high vacuum to high at vacuum at 0.5V height, friction, and current images from by the semiconductor industry. C-AFM channels. Lateral topographyforce microscopybias. The image data0.5V fromtaken bias. The thein data air same taken and in highairsample and vacuum high vacuumafter was was5 scans acquired usingin usingHV identical at identical parameters:~30nN parameters: force with samea probe Iaset 1-2=0.5nA layer MoS2 andsample. V Thebias 1st=1V layer. SinceIn thisSTM study, gives molybdenum a convolution disulfide of topography with electronic same probe with spring constant k of 7N/m, set point of 10nN, and 1Hz scan rate. Scale bar is (LFM) measures the lateral deflection and 2nd layer regions are labeled as 1Ly (MoS ), one of the highly interesting with nominalprobe with spring spring500nm. constant constant at k~ of7N/m 7N/m,. set point of 10nN, and 1Hz scan rate. Scale bar is structure, we see both islands and 2grain boundaries in the heightReferences image. of the laser on the PSD due to torsion, and 2Ly, respectively, in figure 3(a). The 2D materials of transition metal 1. K. S. Novoselov, A. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. 500nm. V. Dubonos, I. V. Grigorieva, &A. A. Firsov. Electric field effect in or twisting, of the cantilever as it scans friction at grain boundaries is higher than dichalcogenides (TMDs) family, was atomically thin carbon films. Science306, 666–669 (2004). across the surface, as depicted in figure the pristine regions, so that they show up investigated on morphological and 2. A. K. Geim & I. V. Grigorieva. Van der Waals Besides just an increase in current, the C-AFM image in HV shows much more detail. From heterostructures. Nature499, 419–425 (2013). 1(e).The difference between thethe forward image in air, it appears that current is relatively homogeneous. Other than the current as dark lines in the friction. By comparing electrical aspects using Park NX-Hivac 3. K. F. Mak, C. Lee, J. Hone, J. Shan, & T. F. Heinz. Atomically and reverse LFM images is proportional the current and friction, we can see that AFM (Park Systems). The differences Thin MoS 2 : A New Direct-Gap Semiconductor. Phys Rev level, not much information can be extracted for the C-AFM in air on this sample. From the Lett105,136805 (2010). to the friction of the materialist differs the dark lines in the friction image match between single and multi-layer was 4. H. Liu, A. T. Neal, Z. Zhu, Z. Luo,X. Xu, D. Tománek,&P. D. Ye. from C-AFM in that a conductivecurrent wire, map taken in HV, in contrast, we can clearly see the grain boundaries in the MoS2 Phosphorene: an unexplored 2D semiconductor with a high the dark lines in the current. However, the observed on AFM topography images. hole mobility. ACS Nano8, 4033–4041 (2014). cut Pt-Ir in our case, is used to measurelayers. current image shows additional features Furthermore, the details of 3D pyramid- 5. J. Zhao, H. Liu, Z. Yu, R. Quhe, S. Zhou, Y. Wang, C. C. Liu, the tunneling current between the probe H. Zhong, N. Han, J. Lu, Y. Yao,&K. Wu. Rise of silicene: A due to the influence of the substrate on like structures due to layer-by-layer competitive 2D material. Prog Mater Sci83, 24–151 (2016). and the sample when the probe is a the local conductivity of the 2D film. growth mechanism was determined at 6. C. R. Dean, A. F. Young, I. Meric, C. Lee, L. Wang, S. few angstroms above the surface. STM Sorgenfrei, K. Watanabe, T. Taniguchi, P. Kim, K. L. Shepard, multi-layer image. & J. Hone.Boron nitride substrates for high-quality graphene can be performed by either keeping electronics. Nat Nanotechnol5, 722–726 (2010). the height constant and recording the 7. X. Xu, W. Yao, D. Xiao, &T. F. Heinz. Spin and pseudospins Using conducting SPM (C-AFM and STM), in layered transition metal dichalcogenides. Nat. Phys.10, current (referred to as constantFigure height 3: Topography image of a3-4 layer MoS2 (a) initially and (b) after 5 successive scans 343–350 (2014). Figure 3: Topography image of a 3-4 layer MoS2 (a) initially and (b) after 5 successive scans at electrical properties of MoS2 were studied mode) or using the feedback to keep 8. G. Fiori, F. Bonaccorso, G. Iannaccone, T. Palacios, D. at 0.1V set point0.1V using set point a using PPP a PPP-NCSTPt-NCSTPt probe probe with spring with constant spring of ~7N/m. constan Scale bart isof 50nm. ~7N/m . Scale bar is both in ambient and high vacuum (HV) Neumaier, A. Seabaugh, S. K. Banerjee,& L. Colombo. the current level constant50nm. and recording condition. Despitethe presence of oxide Electronics based on two-dimensional materials. Nat the height (constant current mode). In layer, clear, homogeneous and higher Nanotechnol9, 768–779 (2014). orders of magnitude in HV. The average detail. From the image in air, it appears 9. X. Xi, L. Zhao,Z. Wang, H. Berger, L. Forró, J. Shan,& K. F. Mak. constant current mode, the height image Strongly enhanced charge-density-wave order in monolayer current level in air is 1.4nA at 5V bias, that current is relatively homogeneous. current signal was measured while in contains both topographic and electronic HV condition. Lastly, topographical, NbSe2. Nat. Nanotechnol.10, 765–769 (2015). while in HV it is 1.1µA. The increase in Other than the current level, not much 10. S. Manzeli, D. Ovchinnikov, D. Pasquier, O. V. Yazyev, &A. Kis. 2D information. C-AFM + LFM for Grain Boundary Analysis electrical, and mechanical information transition metal dichalcogenides. Nat. Rev. Mater.2, 17033 (2017). current level is due to the removal of the information can be extracted for the 11. W. Choi, N. Choudhary, G. H. Han, J. Park, D. thin water layer that is always present C-AFM in air on this sample. From the were obtained for grain boundary Akinwande,&Y. H. Lee. Recent development of two- C-AFM in Air vs High Vacuum analysis using combination of C-AFM and dimensional transition metal dichalcogenides and their When imaging withon the asurface low ofspring the sample constant in air. This probe,current such map astaken P inPP HV,- Cin ONTcontrast,SC wePtwith nominal applications. Mater. Today20, 116–130 (2017). LFM. This approach allowed the finding 12. D. Chiappe, J. Ludwig, A. Leonhardt, S. El Kazzi, A. water layer is particularly problematic can clearly see the Figuregrain boundaries 5: STM in image of multilayer MoS2/sapphire.Cut Pt-Ir wire in constant current mode. In order to demonstratespring the importance constant of 0.2N/m, we can acquire frictional data simultaneously with C-AFM, Figure 5: STM image of multilayer MoS2/ of more specific and detailed structures Nalin Mehta, T. Nuytten, U. Celano, S. Sutar, G. Pourtois, for MoS2 as it p-dopes the material, the MoS2 layers. Iset=0.5nA, Vbias=1V. Scale bar is 200nm.sapphire.Cut Pt-Ir wire in constant current M. Caymax, K. Paredis, W. Vandervorst, D. Lin, S. Degendt, of the water layer on theallowing surface on for correlation between topographic, electrical, and material properties. Figure 3 on grain boundary. K. Barla, C. Huyghebaert, I. Asselberghs, and I. Radu, effectively turning it off electrically. From st 2D materials, we performed C-AFM on 2 mode. Iset=0.5nA, Vbias=1V. Scale bar is 200nm. Layer-controlled epitaxy of 2D semiconductors: bridging shows the height,electrical friction, transport and of current similar CVD images grown fromDespite a 1 the-2 factlayer thatthe MoS C-AFM sample probe is . The 1 layer nanoscale phenomena to wafer-scale uniformity. Accepted the same MoS2 sample in air andnd high and 2 layer regionsMoS2 devices, are labeled the on state as current 1Ly and 2Ly,in respectively, direct contact with in the figure material, 3(a). the The friction at 2D layered material is widely used for Nanotechnology (2018). vacuum (HV), figure 2 (a-b) and (c-d), Scanning Tunneling Microscopy on various research field both industry 13. E. R. Dobrovinskaya, L. A.Lytvynov,& V. Pishchik. Sapphire: respectively. While the topographygrain boundaries is is severely higher degraded than andthe mobility pristine regions,low so force that appliedresults theyConclusion show in no up removal as dark lines in the MoS material, manufacturing, applications. Springer Science & decreases by 40% after exposure to DI ofMoS2 material over the repeated 2 and academy. The characterization and Business Media, 2009. images for the scan in airandfriction. HVare By comparing the current and friction, we can see that the dark lines in the friction exploration of electrical and mechanical 14. B. Radisavljevic, A. Radenovic, J. Brivio, V. Giacometti, & A. Kis. water for two hours.15 scans. Figure 3 shows the topography Single-layer MoS2 transistors. Nat Nanotechnol6, 147–150 (2011). quite similar, the C-AFM images With the ParkNX-Hivac, we were able to properties of 2D material are one of the image match the dark lines in the current. However,image from the the current sameIn samplethis image study, after shows5 molybdenum additional disulfide (MoS2), one of the highly interesting 2D materials of 15. A. Leonhardt, D. Chiappe, I. Asselberghs, C. Huyghebaert,&I. differ considerably. Most notably, the also acquire high quality STM images most critical pointsin materials research Radu. Improving MOCVD MoS 2 Electrical Performance: Impact features due to theBesides influence just an increase of the in substrat current, thee on thescans local in HV conductivity at ~30nNtransition force with of metalthea probe 2D dichalcogenides film. (TMDs) family, was investigated on morphological and of Minimized Water and Air Exposure Conditions. IEEE Electron measured current increases by three without the need for complicated UHV field. The atomic force microscope, a C-AFM image in HV shows much more with nominal springelectrical constant ataspect ~7N/m.s using Park NX-Hivac AFM (Park Systems). The differences between Device Lett38(11) 1606-1609 (2017). single and multi-layer was observed on AFM topography images. Furthermore, the details 12 NANOscientific of 3D pyramid-like structures duewww.nanoscientific.org to layer-by-layer growth mechanismwas determined at NANOscientific 13 multi-layer image.

Using conducting SPM (C-AFM and STM), electrical properties of MoS2 were studied both in ambient and high vacuum (HV) condition. Despitethe presence of oxide layer, clear, homogeneous and higher current signal was measured while in HV condition. Lastly, topographical, electrical, and mechanical information were obtained for grain boundary analysis using combination of C-AFM and LFM. This approach allowed the finding of more specific and detailed structures on grain boundary. Figure 4: (a) Topography, (b) Friction, and (c) current acquired simultaneously on an 1-2 layer as-grown MoS2/sapphire sample. The layer thickness of each2D layered region material is indicated is widely in used(a). for various research field both industry and academy. The Scale bar is 200nm. characterization and exploration of electrical and mechanical properties of 2D material are one of the most critical pointsin materialsresearch field. The atomic force microscope, a versatile imaging and measurement tool, allows us to evaluate 2D materialsin Scanning Tunneling Microscopy on MoS2 multidirectional viewpoints using various imaging modes.This study underlines the improving strategy of material analysis. Moreover, these results emphasize the importance of With the ParkNX-Hivac, we were able to also acquire high qualitymultidirectional STM images and withoutmultichannel the analysis on 2D materials, including the transition metal need for complicated UHV systems and special sample prep/handling.dichalcogenides Figure that 4are shows of high ainterest by the semiconductor industry. 500nm scan of the multi-layer MoS2 sample imaged in constant current mode, with Iset=0.5nA and Vbias=1V. Since STM gives a convolution of topography with electronic structure, we see both islands and grain boundaries in the height image.

References

1. K. S. Novoselov, A. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, &A. A. Firsov. Electric field effect in atomically thin carbon films. Science306, 666–669 (2004). 2. A. K. Geim & I. V. Grigorieva. Van der Waals heterostructures. Nature499, 419–425 (2013). morphological and physical properties using integrated confocal microscopy and atomic force microscopy. We have extended this technology to the study of higher organisms, including measuring the mechanical properties of mammalian tissues and tissue development. These projects demonstrate the power of using nano and micro technologies for the study of biological phenomena. Beyond this work, we are also exploring how biological systems can be emulated in nanoelectronics. We are developing nanoscale electronic devices called memristors that mimic the function of neural synapses in the human brain. As part of that work, we perform extensive characterization of materials and devices, including cutting edge metrology techniques.

Mike Sargeant Award from the Institute of Engineering and Technology, IET, UK), IEEE Nanotechnology Council Early Career Award and the Presidential Early Career Award for Scientists and Engineers (PECASE) Award in 2016. He has published over 140 articles in peer-reviewed journals and given numerous invited talks on his subject areas in national and international conferences and universities. He is also active in the IEEE Electron Devices Society (EDS) serving in various technical committees including IEDM.

Nanoscale Vacuum Channel Transistor on Silicon and Silicon Carbide Figure 1. Integrated confocal microscopy / atomic force microscopy based measurement of bacterial biofilms (Mosier, Cady et al. Journal of MicrobiologicalLong-term Methods, operation 2012). in the harsh environment becomes increasingly less sustainable due to several device aging mechanisms. Total ionizing dose (TID) and displacement damage (DD) degradation limits the new class of missions including long term (> 20 years) deep-space exploration, Presenters at NanoScientific Symposiumnano at-spacecraft, SUNY Polytechnic Europa mission, Sept. 19and-20, so 2019on. In order to tackle such challenges, in this talk, we propose a nanometer scale vacuum channel transistor that combines the advantages of both vacuum and solid- Dr. Jin-Woo Han, Senior Research Scientist at the Centerstate forelectronics, Nanotechnology, providing NASA Ames compactness Research Center as well as high performance.

Our fabricated vacuum channel transistor is introduced and the radiation immunity is experimentally Presenter at NanoScientificassessed. Incident Symposium radiation at SUNY needs Polytechnic to traverse Nov. some 19-20, distance 2019 in the channel to release its energy and Dr. Jin-Woo Han,liberate Senior electrons Research from Scientist the semiconductor at the Center forfor device Nanotechnology, degradation to occur. Therefore, the only approach NASA Ames Researchto completely Center avoid the radiation effects is to utilize a vacuum channel. Unfortunately, as long as the electron emitter and collector structures exist, the vacuum transistor faces mechanical reliability issue NANOSCALEassociated VACUUM with the electrode CHANNEL material rupture TRANSISTOR and degradation in the long term. Our latest results on SiC- ON SILICONbased AND nanoscale SILICON vacuum channel CARBIDE transistor suggest them to be a robust alternative to silicon-based vacuum devices.

Jin-Woo Han is a Senior Research Jin-WooScientist Han at the is aCenter Senior for Research Scientist at the Center for Nanotechnology, NASA Ames Research Center, Moffett Field, Presenter at NanoScientific Symposium at SUNY Polytechnic Sept. 19-20, 2019 California,Nanotechnology, USA. He currently NASA leads Ames a research team composed of USRA personnel responsible for developing nanoscale vacuum transistorResearch for next Center, generation Moffett nanoelectronics Field, and printed electronics. He has received the NASA Ames Honor Award, the IEEE ElectronCalifornia, Device Society USA. EarlyHe currently Career Award, leads Outstanding Engineering Achievement Merit Award from Engineers’ Council, the 2015 Dr. Nathanial Cady, Professor of NanoBioscience, SUNY Polytechnic Institute a research team composed of USRA personnel responsible for developing morphological and physical properties using integrated confocal microscopy and atomic force nanoscale vacuum transistor for Presenter at NanoScientific Symposium at SUNY Polytechnic Nov. 19-20, 2019 next generation nanoelectronics and microscopy. We have extended this technology to the study of higher organisms, including measuring Dr. Nathanial Cady, Professor of NanoBioscience, SUNY Polytechnic Institute printed electronics. He has received the mechanical properties of mammalian tissues and tissue development. These projects demonstratethe NASA Ames Honor Award, the IEEE Prof. Cady obtained his Ph.D. in Microbiology from Cornell University in Ithaca, NY. He is currently a professor Electron Device Society Early Career the powerof nanobioscience of using innano the College and micro of Nanoscale technologies Science (SUNY for Polytechnic the study Institute). of biological Prof. Cady phenomena. has active Beyond this Award, Outstanding Engineering Achievement Merit Award from work,research we are interests also exploringin the development how biological of novel biosensor systems technologies can be andemulated biology-inspired in nanoelectronics. nanoelectronics, We are Our fabricated vacuum channel transistor Unfortunately, as long as the electron including novel hardware for neuromorphic computing. Engineers’ Council, the 2015 Mike developing nanoscale electronic devices called memristors that mimic the function of neural synapsesSargeant in Award from the Institute of is introduced and the radiation immunity is emitter and collector structures exist, Engineering and Technology, IET, UK), experimentally assessed. Incident radiation the vacuum transistor faces mechanical Prof. Cady obtainedthe his human Ph.D. in Microbiology brain. As part from Cornellof that University work, we in Ithaca, perform NY. He extensive is currently characterizationa professor of of materials and devices,IEEE Nanotechnology Council Early needs to traverse some distance in the reliability issue associated with the nanobioscience in the College of Nanoscale Science (SUNY Polytechnic Institute). Prof. Cady has active research Career Award and the Presidential channel to release its energy and liberate electrode material rupture and degradation PROBINGincluding THE INTERSECTIONcutting edge metrology OF techniques. NANOTECHNOLOGY AND BIOLOGY electrons from the semiconductor for device in the long term. Our latest results on SiC- interests in the development of novel biosensor technologies and biology-inspired nanoelectronics, including novel Early Career Award for Scientists and Engineers (PECASE) Award in 2016. He degradation to occur. Therefore, the only based nanoscale vacuum channel transistor hardware for neuromorphic computing. Biology and nanotechnology may has published over 140 articles approach to completely avoid the radiation suggest them to be a robust alternative to appear to exist at distant ends of the effects is to utilize a vacuum channel. silicon-based vacuum devices. in peer-reviewed journals and given spectrum, within the world of science numerous invited talks on his subject (left) Contact mode AFM topography image of the vacuum-channel device’s source-drain interface. The overlaid red line corresponds to the topography line profile displayed. Scan size: 450 x Probingand technology. the At Intersection its core, however, of Nanotechnology and Biology areas in national and international 800 nm. (right) An SCM capacitance image of the region containing the device’s source-drain interface. Brighter colors correspond to relatively more positively charged areas on the device biology is a nanoscale science, one in conferences and universities. He is whereas darker colors correspond to relatively more negatively charged areas. The overlaid green line corresponds to the capacitance line profile. Scan size: 450 x 800 nm. which molecular events govern how also active in the IEEE Electron Devices Biologycells grow, and how nanotechnology organisms function, may appear to exist at distant ends of the spectrum, within the world of Society (EDS) serving in various scienceand how and organisms technology. interact At with its eachcore, however, biology is a nanoscale science, one in which molecular technical committees including IEDM. other. On the other hand, we can gain eventshelpful insightsgovern andhow inspiration cells grow, from how organisms function, and how organisms interact with each other. On NanoScientific Symposium Abstract Awards – Announcing the biologicalother hand, world we as can we gaindevelop helpful insights and inspiration from the biological world as we develop Nanoscale Vacuum Channel engineering solutions at the nano, micro Transistor on Silicon and Silicon Cash1) Best Awards overall for presentation the Best Abstract– Presentations engineering solutions at the nano, micro and macro size scale. In my research group, we leverage NANOSCIENTIFIC SYMPOSIUM PLUS – All Accepted Abstracts Will Be Awarded $100! and macro size scale. In my research Carbide Join our$300 program award by submitting your abstract and not only will you present alongside our Featured Speakers and receive coverage in an upcoming NanoScientific Magazine ABSTRACT AWARDS – issue – but you’ll win $100! Plus, all those chosen to present will be eligible for these additional NanoScientific Abstract Awards, voted on by the symposium attendees: nanotechnologygroup, we leverage to nanotechnology improve our understanding of biological systems, and leverage biological innovations Long-term operation in the harsh 1) Best overall presentation – $300 award environment becomes increasingly Announcing Cash Awards for the 2) Most innovative use of SPM – $300 award to improvedesign and our understandingfabricate unique of . As part of this work, we often need to measure the 3) 2)Best Most industrial innovative or commercial application use of – $300 SPM award – less sustainable due to several device Best Abstract Presentations NanoScientific Symposium Abstract Awards – Announcing size,biological shape, systems, and mechanical and leverage properties various systems. 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16 NANOscientific www.nanoscientific.org NANOscientific 17 2) Mey-Ami, L., Wang, J and Li, F., “Optimization of Single Nanoparticle ICP-MS Analysis for Controlling Nanoparticles in Process Chemicals and UPW used in Wet Surface Cleaning,” Proceedings of International Surface Preparation and Cleaning Conference (SPCC), Portland OR, April 2019. FEATURE UTILIZATION OF SINGLE PARTICLE ICP-MS associated with ICP-MS (e.g. 56Fe vs standard deviation (RSD) was found to needs to be in place soon to begin 3) INTERVIEWWang J., Mey-Ami, L. and Li, F., “A Novel ICP-MS Metrology for Analysis of 40Ar16O). Many of the element’s BED be approximately +/-10%, depending reducing the number of nanoparticlesin ANALYSIS FOR NANOPARTICLE REDUCTION IN values were single nm as the result of on the element. The consistency of the process before the semiconductor Nanoparticles in UPW”, Ultrapure Micro, Phoenix, AZ, June 2019 the optimization. The analysis revealed the results have enabled process manufacturing yield can be improved SEMICONDUCTOR FABRICATION that the nanoparticles found in the “pre” engineers to develop nanoparticle markedly. sample were successfully removed by the specifications in order to achieve quality 10 nm inline filter employed. The results control of incoming process chemicals. Acknowledgement Lisa M. Mey-Ami, Jinjin Wang and Fuhe Li demonstrate the effectiveness of SP ICP- Furthermore, material suppliers can The authors would like to thank Dr. Amir MS for monitoring nanoparticle filtration use the results to guide their efforts in Tavakoli and Ms. Laura Jackson for their Air Liquide Electronics - Balazs NanoAnalysis, Fremont, CA USA efficiency. reducing and removing nanoparticles contributions. Figure1. Nanoparticle Studies: Why Table 2: Results of Various Chemical Samples in Particles/mL needed? from various chemicals they produce. Dr. Lisa Milstein Background Results and Discussion Element 70% Nitric 96% Sulfuric 25% TMAH 30% H2O2 IPA PGMEA Acid Acid Monitoring nanoparticles on a solid part References Mey-Ami is a In order to validate that SP ICP-MS is Mg 200 390,000 NA 8000 2000 NA Figure 2: Au (60nm) NP Standard SEM image surface is a more challenging task. There 1) Mey-Ami, L., Wang, J., Gotts, H and Li, senior scientist suitable and reliable for the analysis Al 7000 1,600,000 NA 56,000 950,000 NA and technical of nanoparticles, a nanoparticle Cu 3500 NA NA 14,000 NA 81,000 hasn't been a suitable technique thus F., “Single Nanoparticle ICP-MS Analysis Fe 5000 640,000 800,000 20,000,000 23,0000 2,500,000 far. Water extracts of OEM parts used of Process Chemicals and UPW Used community standard with a known size and particle Ti 4800 500 600,000 400 6100 2150 leader at Air concentration was prepared and studied. Zn 200 17,000 NA 1000 83,0000 NA in etching and deposition chambers in Surface Cleaning and Preparation”, Liquide Balazs Cr 200 21,000 40,000 22,000,000 15,000 58,000 (quartz part, ceramic part and Aluminum Proceedings of International Surface Sn 150 NA NA 70,000,000 NA 9500 coupon) were evaluated for nanoparticles Preparation and Cleaning Conference in Ni 400 NA 200,000 25,000,000 NA NA Ta NA NA 12,000,000 NA NA NA by SPICPMS. Figure 5 shows SP ICP-MS (SPCC), Cambridge, MA, April 2018. Dr. Fremont, Lisa CA. Milstein Her specialties Mey include-Ami is a FigureSinglesenior 1:nm Nanoparticle -100 nmscientist particles Studies: are now Why critical.and Needed? technical community leader at Air NA = not available concentration results for a variety of 2) Mey-Ami, L., Wang, J and Li, F., trace element analysis of advanced SingleMonitoring nm -100& controlling nm particles single near are 1now nm particlescritical. will soon be required. Liquidematerials, thinBalazs films and in single Fremont, CA.Monitoring Her & controlling specialties single near 1 nm include trace element analysis of Table 2: Results of Various Chemical Samples in Particles/mL analytes for these three parts expressed “Optimization of Single Nanoparticle ICP- particles will soon be required. in particles/cm2Figure (surface 5: Nanoparticles area). Found MS Analysis for Controlling Nanoparticles advancednanoparticle analysismaterials, by ICP-MS. thin Prior films and single nanoparticle analysis by ICP-MS. Prior to From the Surface of Various OEM Parts to joining Air Liquide Balazs in 2007 Figure 1 illustrates the importance of SP ICP-MS has also been used to in Particles/cm2 in Process Chemicals and UPW used in joining Air Liquide Balazs in 2007 she worked as a research chemist at RTI International characterize various process chemicals. Wet Surface Cleaning,” Proceedings of she worked as a research chemist at currently being able to detect particles l inRTI Durham, International NC.in Durham, She NC. received She herbetween Ph.D. single nmin andanalytical 100 nm as chemistry from the University of Table 2 shows SPICP-MS nanoparticle International Surface Preparation and concentrations for various analytes Cleaning Conference (SPCC), Portland OR, Cincinnati.received her Ph.D. in analytical chemistry sub 10-nm scale devices have been in Figure 2: Au (60nm) NP Standard SEM image from the University of Cincinnati. production since 2018. Soon it will be in acid samples (e.g. 70% nitric acid April 2019. necessary to monitor near 1 nm particles Figure 2 shows a scanning electron and 96% sulfuric acid), base samples: 3) Wang J., Mey-Ami, L. and Li, F., “A Introduction as the semiconductor technical node microscope (SEM) image of a60 nm (e.g. 25% tetramethylammonium Novel ICP-MS Metrology for Analysis of Nanoparticles are defined as ultrafine continues to scale down. commercial Gold (Au) nanoparticle hydroxide; TMAH), oxidizers: (e.g. 30% Nanoparticles in UPW”, Ultrapure Micro, particles with at least one dimension standard. Figures 3 and 4 show the hydrogen peroxide; H2O2), and organic Phoenix, AZ, June 2019 solvents: (e.g. isopropyl alcohol; IPA in the nano-scale (1-100nm) range. ICP-MS is routinely used for the time-resolved particle signal profile and Figure 3. 60 nm Au Particle Standard: SP-ICP-MS Naturally occurring nanoparticles, determination of trace elements in the particle size distribution of the Au and propylene glycol methyl ether Figure 5: Nanoparticles Found From the Surface of Various OEM Parts in Particles/cm2 present as unwanted contaminants UPW, process chemicals and extraction standard by SP ICP-MS, respectively. As acetate, PGMEA). These are all common in all aspects of the semiconductor solutions for OEM tool parts 1-3. The can be seen, the particle size distribution processchemicals used in semiconductor manufacturing processes, are detection limits are often as low as clearly shows that the median Au particle manufacturing processes such as Conclusion increasingly important to characterize. As sub parts per trillion (ppt). Since the size is centered at 60 nm with a narrow cleaning, developing, etching, planarizing SPICP-MS methods have been developed Table 1: Results of a UPW Sample in Particles/mL and photoresist stripping. Again, ICP-MS in our laboratory and regularly applied

the world of electronics become smaller analytes dissolve completely and aspirate distribution. Intensity Signal parameters were optimized to eliminate to water, chemicals and OEM parts approaching 5 nm technical node, into the ICP plasma continuously, Element Pre Filtration Post Filtration BED Particle Particle (nm) interferences (e.g.48Ti vs 32S16O in used throughout semiconductor nanoparticles are crucial contaminants producing a constant signal intensity, concentration Concentration a sulfuric acid matrix) and enhance manufacturing processes. The processes that need to be monitored and then only total elemental concentration is Al 98 * 8 removed from the processes to avoid determined. Using time resolved data Mg 180 * 6 overall analysis sensitivity. A large include wafer surface cleaning and Time (sec) B 120 40 15 amount of nanoparticles was found in preparation, chemical mechanical device failure. acquisition with short dwell times (a Zn 110 * 11 60 nm Au Particle Standard: SP-ICP-MS the process chemicals, although the planarization (CMP), deposition, data point is collected every 0.1 ms), Ti 65 * 6 This paper describes single particle the transient signal of each individual Fe 800 110 4 elemental composition of nanoparticles etching, implantation, and lithography. Cr * * 3 varied. Some of the nanoparticle The analytical results produced have Figure 4. 60 nm Au Particle Standard: SP-ICP-MS inductively coupled plasma-mass nanoparticle can be differentiated from As * * 5 contaminants were likely introduced been used by chipmakers, OEM’s and spectrometry (SP ICP-MS). With the the steady-state ICP-MS signal generated V 60 * 5 technique, we have evaluated ultrapure by the dissolved species. This unique * = not detected during the chemical manufacturing raw material suppliers in monitoring water (UPW), process chemicals and the feature, coupled with the assumption of Table 1: Results of a UPW Sample in Particles/mL process. For example, Tantalum (Ta) nanoparticles in their processes. The surface of various original equipment spherical particle size, enables ICP-MS Table 1 shows SPICP-MS results for nanoparticles found in TMAH were the results we obtained showed that a manufacturer (OEM) parts. Figures to characterize nanoparticles down to a UPW sample, pre and post 10 nm direct result from using Ta electrodes in large number of nanoparticles was of merit presented include particle single nm sizes producing various results: in line filtration. The samples were the electrochemical synthesis of TMAH. present in various process chemicals concentration (particles/mL or particles/ particle concentration, particle median analyzed for a variety of elements that The Tin (Sn) nanoparticles found in H2O2 and on the surface of OEM plasma cm2), median particle size (nm), size size, size distribution information, commonly form nanoparticles in an were due to the addition of an inorganic etch and deposition equipment parts. distribution, and background equivalent elemental composition and background aqueous solution and also critical to Sn-based stabilizer. The decomposition The presence of these nanoparticle diameter (BED). BED is related to the equivalent diameter (BED). There is semiconductor manufacturing. The ICP- of the Sn compound caused the contaminantscan cause random device smallest particle size that can be detected no other analytical methods to date, MS instrument parameters (e.g. reaction formation of Tin nanoparticles in defects and would have a detrimental and often as low as single digit nm. which can provide all these parameters gases) were optimized to combat the H2O2. The precision of SP ICP-MS impact on current and next generation Size (nm) simultaneously for nanoparticles. molecular and isobaric interferences analysis was studied and the relative semiconductor manufacturing. A strategy 60 nm Au Particle Standard: SP-ICP-MS

18 NANOscientific www.nano-scientific.org www.nanoscientific.org NANOscientific 19 Neutrinos move at or very near the velocity of light, have no electric charge, and have so little mass that until very recently scientists were not sure if neutrinos have any mass at all. Until recently, when in 1988 neutrino oscillation was discovered by the Super-Kamiokande experiment

Neutrinos move at or very near the velocity of light, have no electric charge, and have so little mass that until very recently scientists were not sure if neutrinos have any mass at all. Until recently, when in 1988 neutrino oscillation was discovered by the Super-Kamiokande experiment

The next phase in this project is the NEUTRINOS ARE AMONG SUPERNOVA proposed Hyper-Kamiokande (HK), to be constructed in Kamioka, Hida THE MOST ABUNDANT 1987A, WHICH City, Gifu Prefecture, expected to start PARTICLES IN THE NEUTRINO OCCURRED sometime in 2020 with eight times ON FEBRUARY larger fiducial mass than Super K. UNIVERSE, A BILLION ASTROPHYSICS: 23, 1987. Hyper K will be equipped with newly TIMES MORE ABUNDANT THE RIGHT developed high-sensitivity photosensors. THAN THE PARTICLES SEEING THE FIGURE SHOWS The aim of HK is toPictured: elucidate Supernova the Grand 1987A, which occurred on February 23, 1987. The right figure shows before explosion. Unified Theory and the history of the BEFORE （Anglo-Australian Observatory/David Malin) A supernova explosion happens when a star at least 8 times more THAT MAKE UP evolution of the universe through an QUANTUM EXPLOSION. investigation of protonmassive decay than and the sun collapses. An enormous amount of energy (more than 99% of energy emitted from the Sun STARS, PLANETS AND (Anglo-Australian CP violation (the differencefor 4.5 billion between years) is released primarily in the form of neutrinos in just 10 seconds. A supernova explosion is PEOPLE. NEUTRINOS Observatory/ neutrinos and antineutrinos),expected to as occur well inside our galaxy once every 10 to 50 years. If such an explosion occurs, Super-Kamiokande is UNIVERSE David Malin) as the observation of neutrinos from expected to detect about 8,000 neutrinos. and be able to reveal the mechanism of supernova explosions by ARE PRODUCED supernova explosions.analyzing Seed fundingthe information for of the energy and the arrival time of these neutrinos. Pictured:A supernova Supernova explosion happens 1987A, when which a occurredThey plan on toFebruary "dissolve gadolinium23, 1987. inThe right figureHyper-Kamiokande shows before (HK) hasexplosion. already been IN UNIMAGINABLE star at least 8 times more massive than the the tank around the end of this year or allocated for the current Japanese fiscal （Anglo-Australian Observatory/David Malin) A supernova explosion happens when a star at“Since least neutrinos 8 times interactmore only weakly with matter they can be used to investigate both the deep interior of stars and the far QUANTITIES BY THE SUN sun collapses. An enormous amount of the beginning of next year in order to year, and 12 countries,reaches including of the Japan,universe. For example, we can observe not only the core of our sun, whose nuclear fusion creates the light that energy (more than 99% of energy emitted enter a new phase of observation. “We massive than the sun collapses. An enormous amount of energy (more than 99%expressed of energy interestpowers emittedin the project. the from Earth, the but Sun also the moment when the central core of a massive star collapses as a supernova burst using the AND STARS. COULD THEY forfrom 4.5 the billion Sun for years)4.5 billion is years)released is released primarily can in detect the formsupernova of neutrinos neutrinos from in just 10 seconds. A supernova explosion is They plan to "dissolve gadolinium in the tank around the end of thisneutrinos year or thesethe beginning processes of nextcreate.” year Dr.in order Masayuki to Nakahata, Director, Super-Kamiokande Collaboration expectedprimarily in tothe occur form of inside neutrinos our in galaxyjust 10 oncethe every beginning 10 toof the 50 universe, years. If improve such an explosion occurs, Super-Kamiokande is BE THE DARK MATTER seconds. A supernova explosion is expected enpointingter a new accuracy phase of for observation. galactic supernova, “We can detect supernova neutrinos from the beginning of the universe, expected to detect about 8,000 neutrinos. and be able to reveal the mechanismMASAYUKI of supernova explosions by THAT CONTROLS THE to occur inside our galaxy once every 10 improvereduce backgroundpointing accuracy for nucleon for galactic supernova, reduce background for nucleon decay searches, and etc.,” analyzingto 50 years. theIf such information an explosion occurs,of the energydecay and searches,the arrival and timeetc.,” explains of these Dr. neutrinos.NAKAHATA explains Dr. Nakahata. is the Director, Super-Kamiokande is expected to detect Nakahata. FATE OF THE UNIVERSE Kamioka “Sinceabout 8,000 neutrinos neutrinos. interact and be only able weakly to reveal with matter they can be used to investigate both the deep interior of stars and the far observatory, OR EXPLAIN WHY WE reachesthe mechanism of the ofuniverse. supernova For explosions example, by we can observe not only the core of our sun, whose nuclear fusion creates the light that ICRR the powersanalyzing the the Earth, information but also of the the energy moment and when the central core of a massive star collapses as a supernova burst using the LIVE IN A UNIVERSE University of the arrival time of these neutrinos. neutrinos these processes create.” Dr. Masayuki Nakahata, Director, Super-KamiokandeTokyo Collaboration and OF MATTER AND NOT Spokesperson ANTIMATTER? WORLD- “SINCE NEUTRINOS for the Super- INTERACT ONLY WEAKLY Kamiokande Masayuki Nakahata is the Director, Kamioka observatory, ICRR the University of Tokyo and CLASS, MULTIPURPOSE WITH MATTER THEY CAN Collaboration Spokesperson for the Super-Kamiokande Collaboration in Gifu-ken, Japan. The Super-Kamiokande is operated by in Gifu-ken, DETECTORS DESIGNED BE USED TO INVESTIGATE an international collaboration of about 150 people and about 40 institutes from Japan, the United States, Korea, BOTH THE DEEP INTERIOR Japan. The Super-Kamiokande TO SOLVE THE PUZZLE is operated byChina, an international Poland, Spain, Canada, UK, Italy and France. Blazar emitting neutrinos and gamma rays. Photo Credit Ice Cube/NASA OF STARS AND THE Blazar emitting neutrinos and gamma rays. Photo Credit Ice Cube/NASA collaboration ofIn aboutJanuary, 150 peopleSuper –K was restarted after work was done in 2018 to stop a water leak in the tank. “The very precise ABOUT NEUTRINOS FAR REACHES OF THE and about 40 institutes from Super-Kamiokande is the large water atmospheric neutrinos and man-made Japan, the Unitedtest States, done Korea,in early February showed that water leak is completely fixed,” explained Dr. Nakahata, “We filled pure Cherenkov detector located in Gifu neutrinos. In 1998, from the observation UNIVERSE. FOR EXAMPLE, ARE DISCUSSED IN THIS China, Poland, Spain, Canada, UK, NeutrinoJapan. Astrophysics: The construction was started Seeing of atmospheric the Quantum neutrinos we discovered Universe WE CAN OBSERVE NOT ONLY water to the tank from last October to January. In this time, we recirculated water even filling phase. Because of Italy and France. ARTICLE ALONG WITH in 1991 and the observation began on the neutrino oscillations which neutrinos THE CORE OF OURMasayuki SUN, NakahataPictured is the Neutrino Director, oscillation Kamioka was observatory, ICRR the Universitythis new ofscheme, Tokyo waterand transparency has been very good even just after the tank was full and we have been taking In January, Super –K was restarted April 1st, 1996 are changing their types in flight. In Pictureddiscovered Neutrino by oscillation the Super-Kamiokande was discovered by the Super-Kamiokande experiment in 1998.Neutrinos exhibit the properties of a particle as well FIRST HAND UPDATES SpokespersonWHOSE NUCLEAR for the SuperFUSION-Kamiokande Collaboration in Gifu-ken, Japan. The afterSuper work-Kamiokande wasgood done data in is2018 inoperated toSK -V.” by Neutrinos are among the most abundant particles in the2001, universe, solar neutrino a billionoscillations times were more abundant than the asexperiment a wave. Therefore, in 1998.Neutrinos neutrino1, neutrino2 exhibit and neutrino3, each with different mass eigenstates, travel through space as waves that have a different CREATES THE LIGHT THAT frequency. The flavor of a neutrino is determined as a superpositionstop of athe water mass eigenstates. leak in the The tank. type of the flavor oscillates, because the phase The Super-Kamiokande detector consists discovered by the observation of solar an international collaboration of about the150 properties people ofand a particle about as 40 well institutes as a from Japan, the United States, Korea, FROM particlesTWO OF thatTHE make up stars, planets and people. Neutrinos are produced in unimaginable quantities by the of the wave changes This phenomenon is called neutrino oscillation.“The Neutrino very precise oscillation test occurs done when in neutrinos have mass and non-zero mixing. of a stainless-steel tank, 39.3m diameter neutrinos. In 2011, the third neutrino POWERS THE EARTH, BUT wave. Therefore, neutrino1, neutrino2 China, Poland, Spain, Canada, UK, Italy and France. early February showed that PHYSICISTS WORKING IN and 41.4m tall, filled with 50,000 tons of oscillation mode was discovered by man- ALSO THE MOMENT WHEN and neutrino3, each with different mass Sun and stars. Could they be the dark matter that controls the fate of the universe or explain whyIn we January, live in Super a –K was restarted after work was done in 2018 to stop a waterwater leak leak in the is completely tank. “The fixed,” very precise ultra pure water. About 13,000 photo- made neutrino observation. THE CENTRAL CORE OF A eigenstates, travel through space as THIS AREA. THE DETECTOR explained Dr. Nakahata, “We universe of matter and not antimattermultipliers are installed? World on the-class, tank wall. multipurpose detectors designed to solve thetest puzzle done about in early February showed thatwaves water that leak have is a differentcompletely frequency. fixed,” explained Dr. Nakahata, “We filled pure MASSIVE STAR COLLAPSES The next phase in this project is the proposed Hyperfilled-Kamiokande pure water (HK), to the to tank be constructed from in Kamioka, Hida City, The detector is located at 1,000 meter Neutrinos move at or very near the The flavor of a neutrino is determined as RESEARCHneutrinos AIMS are TO discussed GET in this article along with first hand updates from two of the Physicists workingwaterAS A SUPERNOVAto thein this tank from BURST last October toGifu January. Prefecture, In this expected time, towe start recirculated sometime in water 2020last with October even eight filling to times January. phase. larger In fiducial thisBecause mass of than Super K underground in the Kamioka-mine, Hida- velocity of light, have no electric a superposition of the mass eigenstates. time, we recirculated water even A CLEARER PICTURE OF city, Gifu, Japan. charge, and have so little mass that thisUSING new THEscheme, NEUTRINOS water transparency hasThe beentype of very the flavor good oscillates, even just after the tank was full and we have been taking area. The detector research aims to get a clearer picture of the universe, creating a new era of science: Hyper K will be equipped with newly developed highfilling-sensitivity phase. photosensors. Because of this The new aim of HK is to elucidate the until very recently scientists were not THESE PROCESSES because the phase of the wave changes THE UNIVERSE, CREATING good data in SK-V.” Grand Unified Theory and the history of the evolutionscheme, of the water universe transparency through an has investigation of proton decay and One of the purposes of theneutrino Super- astrophysics.sure if neutrinos have any mass at all. CREATE.” DR. MASAYUKI This phenomenon is called neutrino been very good even just after the Kamiokande experiment is to reveal Until recently, when in 1988 neutrino CPoscillation. violation (theNeutrino difference oscillation between occurs neutrinos and antineutrinos), as well as the observation of neutrinos from A NEW ERA OF SCIENCE: NAKAHATA, DIRECTOR, tank was full and we have been the neutrino properties through oscillation was discovered by the supernovawhen neutrinos explosions. have Seedmass funding and non-zero for Hyper -Kamiokande (HK) has already been allocated for the current NEUTRINOSuper-Kamiokande ASTROPHYSIC is theS. large water Cherenkov detector located in Gifu Japan. The construction wasSUPER-KAMIOKANDE started in Japanese fiscal year, and 12 countries, including Japan,taking expressed good data interest in SK-V.” in the project. the observation of solar neutrinos, Super-Kamiokande experiment. COLLABORATION mixing. 1991 and the observation began on April 1st, 1996

20 NANOscientific www.nanoscientific.org NANOscientific 21 The Super-Kamiokande detector consists of a stainless-steel tank, 39.3m diameter and 41.4m tall, filled with

50,000 tons of ultra pure water. About 13,000 photo-multipliers are installed on the tank wall. The detector is located at 1,000 meter underground in the Kamioka-mine, Hida-city, Gifu, Japan.

One of the purposes of the Super-Kamiokande experiment is to reveal the neutrino properties through the observation of solar neutrinos, atmospheric neutrinos and man-made neutrinos. In 1998, from the observation of atmospheric neutrinos we discovered the neutrino oscillations which neutrinos are changing their types in flight. In 2001, solar neutrino oscillations were discovered by the observation of solar neutrinos. In 2011, the third neutrino oscillation mode was discovered by man-made neutrino observation. all possible information, in neutrinos, photons, and other astrophysical messengers, like gravitational waves.

Do you think the Hyper K proposal will be approved and why is it important?

It can be harder to make funding predictions than supernova ones! Hyper-K is certainly a good prospect. It will see a truly enormous number of neutrinos (actually, mostly antineutrinos) from a supernova. The Deep Underground Neutrino Experiment (DUNE) in the U.S. is also a good future prospect. It will see fewer neutrinos than Hyper-K, but because it’s made of argon rather than water, it will see mostly neutrinos, whereas Hyper-K will see antineutrinos. This will bring us unique information about, for example, the star’s collapse into a neutron star. JUNO in China is another future large detector, to be made of hydrocarbon, which will see antineutrinos. AN INTERVIEW WITH DR. KATE SCHOLBERG KATE SCHOLBERG is a Professor of Physics at Duke University where her broad research interests TWO SCIENTISTS FROM THE TANDEN SCHOOL include experimental Deep Underground Neutrino Experiment (DUNE) elementary particle OF ENGINEERING NEW YORK INTERESTED IN physics, astrophysics Deepburst, Underground will send Neutrino a datagram Experiment to (DUNE)the central, will be the largestabout, particle for example,physics project the ever star’s to be collapse built in the United States. Hosted and cosmology. bySNEWS the U.S. Department computer. of Energy’sIf this computer Fermilab, this internationalinto project a neutronbrings together star. more JUNO than in 1,000 China scientists is from more than 30 NEUTRINO MASS DETECTION USING AFM Her main specific countriesreceives around at least the world, two alldatagrams dedicated to indicating unraveling the mysteriesanother of ghostly future partic largeles calleddetector, neutrinos. to be To do this, Fermilab will send interests are in neutrino physics. Dr. itsbursts world-leading within particle 10 seconds beam 800 of miles each (1,300 other, kilometers) it throughmade the of earth hydrocarbon, to four gigantic which detectors will built see a mile beneath the surface Kate Scholberg is a Professorat the Sanford of UndergroundPhysics at ResearchDuke University Facility in South where Dakota. her A liquid broad-argon neutrino detector, pre-excavation work is in full swing at Scholberg studies neutrino oscillations thesends site in outLead, an South alert Dokat message.a. Individual antineutrinos. Deep Underground research interests include experimental elementary particle physics, astrophysics and cosmology. Her main with the Super-Kamiokande experiment experiments, if they have really clean Neutrino Experiment (DUNE), will be the specific interests are in neutrino physics. Dr. Scholberg studies neutrino oscillations with the Super-Kamiokande where her primary involvement is with Cansignals, we create can imagesalso send of the individual Elusive Neutrinos alerts, but Using largest AFM/SPM? particle physics project ever to be experiment where her primary involvement is with the atmospheric neutrino data analysis, which in 1998 yielded the atmospheric neutrino data analysis, two or more at the same time will mean built in the United States. Hosted by the the first convincing evidence for neutrino oscillation (implying the existence of non-zero neutrino mass). which in 1998 yielded the first convincing “Well,we are I think sure AFM, that SEM,something etc. won’t happened. be of much use, I’mU.S. afraid,” Department says Dr. of Scholberg Energy’s Fermilab,“One cannot directly see a neutrino. What one does see is the tracks or other evidence of charged particles that result from the rare evidence for neutrino oscillation (implying this international project brings together for measurement of neutrino mass with In our proposal, a sample containing interaction of the neutrino with matter, and one can make images out of this information. There are a lot of LORCAN M. An Interviewthe existence with Dr. of non-zeroKate Scholberg neutrino mass). Unfortunately the kind of core-collapse more than 1,000 scientists from more AFM. 5x10-10 kg of radioactive antimony different detector technologies. Usually the images are electronic: for example, the charged particles make FOLAN, Cherenkovsupernova light, burst and that then would photo resultsensors in capture a andthan digitize 30 countriesthe photons, around making the lovely world, ring all images. In other “My collaborator, Vladimir Tsifrinovich atoms must be attached to an AFM tip in Why do you think understanding Neutrinos is so important and how might it help us understand the universe? Department Chair, Why do you think understanding detectors,SNEWS alert like DUNE is really (a “time rare— projection it will happen chamber”), dedicatedthe charged to particles unraveling from thethe mysteriesinteraction ofionize liquid argon, and I are very interested in neutrinos. order to produce a 1 pN recoil force at a Applied Physics, NYU How isNeutrinos Neutrino research is so important impacting and physics? how andonly the about ionization every charge 30 years is drifted or so in in a the high Milky electric ghostlyfield placed particles on the called argon, neutrinos.and then collected To do to make an Of the fundamental particles, they are temperature of 25 mK. If this force could Tandon School might it help us understand the imageWay. in We the have projected no good shape way of a of track. predicting The time atthis, which Fermilab the charge will arrives send onits anworld-leading anode plane gives the third perhaps the most enigmatic. Subsequent be detected, we could discuss the use of of Engineering Neutrinosuniverse? are fundamental How is Neutrino particles, research like electrons dimension. andwhen quarks, or where Scintillation and it we happens need detectors to next, understand like although JUNO just the see propertiesparticle flashes of beam oflight, the 800captured miles in (1,300 photo kilometers) sensors, when the work indicates that the sensitivity AFM for the neutrino mass measurement. impacting physics? neutrinos create charged particles.” required to make a measurement is So far, even this initial experiment has not fundamental constituents of matter if we are to understandwe can keep the “bigan eye picture” on some of Nature.red giant Neutrinos through also played the earth a to four gigantic Neutrinos are fundamental particles, stars, like Betelgeuse, which might blow up detectors built a mile beneath the surface beyond current technology, but we are been implemented. role in the early Universe. It is very likely that neutrinos were important in the generation of matter at very early like electrons and quarks, and we need Twoany scientists minute (or from 10,000 the yearsTanden from School now-- of it’s Engineering at the SanfordNew York Underground interested in Research Neutrinos investigated still working on finding a method that times into theunderstand Universe’s the history. properties One of theof the huge questionsusinghard AFM. to tellout for there an individual is why we star).have Somean enormous Facility excess in of South Dakota. A liquid-argon VLADIMIR will work.” Lorcan M. Folan, Department What/how does technology need to matterfundamental today, rather constituents than antimatter, of matter given if that thestars, properties in the monthsof matter and and days antimatter before they are almostneutrino symmetric. detector, pre-excavation work Chair, Applied Physics, NYU Tandon advance to make this measurement? Their paper titled “Generation of a directed mono-energetic neutrino beam and measurement of the neutrino TSIFRINOVICH we are to understand the “big picture” of blow up, may produce extra neutrinos, is in full swing at the site in Lead, South School of Engineering. “Our opinion is We believe that the first step could be Neutrinos were probably involved in the generationmass of "the was matter a proposal-antimatte for a methodr imbalance. to measure Therefore the rest we mass need of the to neutrino emitted in electron capture beta Industry Professor, Nature. Neutrinos also played a role in the and we will be watching for that too, but Dakota. that every proposal, including our AFM achieved with current AFM technology. If understand the properties of neutrinos in order todecay. figure We out study how generation the Universe of a directional became mono so -matterenergetic-heavy. neutrino beam in electron capture beta-decay and analyze the Sr. Lecturer, Applied early Universe. It is very likely that neutrinos such a presupernova neutrino signal proposal, should be pursued further.” it is done, one will need to increase the recoil force exerted by neutrinos. We consider the influence of the neutrino rest mass on the recoil force and discuss the Physics, NYU Tandon were important in the generation of matter opportunitywould be for so neutrino faint that mass we measurement could only using see an it atomic Can force we microscopy create images(AFM). We of compute the Elusive the enhancement of the sensitivity of the measurement in order to Can you briefly explain how SNEWS gathers information about Supernovas? And do you have any theory on when School of Engineering at very early times in the Universe’s history. for very nearby stars (Betelgeuse is one of Neutrinos Using AFM/SPM? Why is the Neutrino particle the measure the neutrino mass. the nextOne event of the might huge occur? questions out there is why them). The rarity of such a stellar blowout “Well, I think AFM, SEM, etc. won’t be of most enigmatic of the fundamental we have an enormous excess of matter does mean that it’s especially important much use, I’m afraid,” says Dr. Scholberg particles? Why is a method for this today, rather than antimatter, given that According to the Standard Model measurement important and is it SNEWS (Supernova Early Warning System) is a networkto be of prepared, large underground so that we neutrinocan capture detectors. “One Any onecannot of these directly see a neutrino. Their paper titled “Generation of a the properties of matter and antimatter neutrinos do not have rest mass. possible for AFM (if improved) to detectors would see an intense burst of neutrinos withinall possible about information,10 seconds if in a neutrinos, star’s core collapsesWhat in theone Milky does see is the tracks or other directed mono-energetic neutrino beam are almost symmetric. Neutrinos were photons, and other astrophysical evidence of charged particles that result However oscillation experiments show make this measurement? Way. Any of the detectors, if they see such a burst, will send a datagram to the central SNEWS computer. If this and measurement of the neutrino mass" probably involved in the generation of the that they do have a mass. Thus, neutrino There are currently a few proposals for messengers, like gravitational waves. from the rare interaction of the neutrino was a proposal for a method to measure computermatter-antimatter receives at least imbalance. two datagrams Therefore indicating bursts within 10 seconds of each other, it sends out an alert is the only fundamental particle which the neutrino mass measurement. None with matter, and one can make images the rest mass of the neutrino emitted message.we need Individual to understand experiments, the properties if they have of really clean signals, can also send individual alerts, but two or more cannot be described in the scope of the of them has succeeded. Our opinion is Do you think the Hyper K proposal will out of this information. There are a lot of in electron capture beta decay. We at the neutrinossame time in will order mean to figure we are out really how sure the that something happened. Standard Model. There are believed to be that every proposal, including our AFM be approved and why is it important? different detector technologies. Usually study generation of a directional mono- Universe became so matter-heavy. three neutrino types or flavors (electron, proposal, should be pursued further. It can be harder to make funding the images are electronic: for example, energetic neutrino beam in electron muon and tau) and three neutrino Unfortunately the kind of core-collapse supernova burstpredictions that would than resultsupernova in a SNEWS ones! Hyper-K alert is reall they rare charged— it will particles make Cherenkov capture beta-decay and Can you explain how SNEWS gathers is certainly a good prospect. It will see light, and then photo sensors capture and masses, but there is not a one to one How are discoveries about Neutrino happen only about every 30 years or so in the Milky Way. We have no good way of predicting when or where it analyze the recoil force exerted by information about Supernovas? And do correspondence between the flavors and likely to change physics as we a truly enormous number of neutrinos digitize the photons, making lovely ring neutrinos. We consider the influence of happenyou next, have although any theory we can on keep when an the eye next on some red giant stars, like Betelgeuse, which might blow up any the masses. And the mass ordering and understand it today? What do you (actually, mostly antineutrinos) from images. In other detectors, like DUNE (a the neutrino rest mass on the recoil force minuteevent (or 10,000 might years occur? from now-- it’s hard to tell for an individual star). Some stars, in the months and days flavor mixings are still unknown. think it might explain about the a supernova. The Deep Underground “time projection chamber”), the charged and discuss the opportunity for neutrino beforeSNEWS they blow (Supernova up, may Earlyproduce Warning extra System) neutrinos, and we will be watching for that too, but such a presupernova universe? Neutrino Experiment (DUNE) in the particles from the interaction ionize liquid mass measurement using an atomic is a network of large underground Can you explain why the current Discoveries about neutrinos could neutrino signal would be so faint that we could onlyU.S. see isit alsofor very a good nearby future stars prospect. (Betelgeuse It is oneargon, of them). and the ionization charge is drifted force microscopy (AFM). We compute the neutrino detectors. Any one of these technology was not capable of the generate a new theory of baryonic matter will see fewer neutrinos than Hyper-K, in a high electric field placed on the argon, enhancement of the signal-to-noise ratio detectors would see an intense burst but because it’s made of argon rather and then collected to make an image image? beyond the standard model. It could also The rarity of such a stellar blowout does mean that it’s especially important to be prepared, so that we can capture due to signal accumulation (averaging), of neutrinos within about 10 seconds if As the first step to the AFM neutrino mass help to understand the mysterious dark than water, it will see mostly neutrinos, in the projected shape of a track. The find the optimal time for signal a star’s core collapses in the Milky Way. experiment, one should detect the recoil matter and asymmetry between matter whereas Hyper-K will see antineutrinos. time at which the charge arrives on an accumulation and formulate conditions Any of the detectors, if they see such a This will bring us unique information anode plane gives the third dimension. force produced by neutrino radiation. and antimatter in our Universe.

22 NANOscientific www.nanoscientific.org NANOscientific 23 APPLICATION FEATURE PARK SYSTEMS ANNOUNCES 2019 PARK AFM SCHOLAR NOTE PROBIOTIC BACTERIA TOPOGRAPHY AND ARTICLE LILIANG HUANG, PHD NORTHWESTERN UNIVERSITY NANOMECHANICAL PROPERTIES ANALYSIS USING ATOMIC FORCE MICROSCOPY Liliang Huang is nanoparticles of up to five elements (Au, Ag, catalyst, which was determined to be from The Mirkin Cu, Co, and Ni) by using a simple two-step 7 times more active on a Pt-to-Pt basis GABRIELA MENDOZA, BYONG KIM AND KEIBOCK LEE, PARK SYSTEMS, INC., SANTA CLARA, CA, USA Research Group thermal annealing treatment. This synthetic than the “gold standard” commercial at Northwestern Park Systemsroute Announces forms 2019 a versatile Park AFM Scholar platform Liliang Huang for, PhDstudying Northwestern UniversityPt catalyst. Herein, this work is a proof- Introduction Liliang Huang is from The Mirkin Research Group at Northwestern University which has pioneered the use of nanoparticle- University which biomoleculethe conjugates catalysis-related as synthons in materials science properties and the development of of many the nanoparticle -based extra- and intracellularof-concept for a powerful tool used to Probiotics are living microorganisms has pioneered the biodiagnosticnanoparticles. and therapeutic tools. In this work, by effectively discover new catalysts. We believe that that provide numerous health benefits Figure 1. a) use of nanoparticle- Researchutilizing summary SPBCL in combination with density more variables could be explored with Adhesion energy, Hydrogen is widely used as a clean, renewable alternative to fossil fuels, while water electrolysis represents to the host when supplied in adequate an increasingly important method for industrial hydrogen manufacturing (~5% of the market). Currently, platinum is b) adhesion force biomolecule extensivelyfunctional used as a hydrogen theory evolution reaction (DFT) (HER) electrocatalystcalculations, for water electrolysis we ; however, its scarcitythis and technology, leading to catalysts that amount as well as improve the intestinal high costlimits its practicality in electrolyzers. The key motivation of my graduate studies is focused on developing and c) height conjugates as novel strategiesintroduced to discover, design a andnovel fabricate strategy cost-effective HER to electrocatalysts. design and will likely even exceed in performance microflora of the host. Probiotics are Nanoparticles are emerging as attractive HER electrocatalysts for researchers due to their enhanced activity images taken synthons in materials science and the when compareddiscover to their bulk cost-effective counterparts. Pt-based multimetallic HER nanoparticleselectrocatalysts. are particularly interesting becausethan the one we identified here through mainly administered to humans combined alloying Pt with earth abundant transition metal elements (e.g. Cu) is found to be favorable for activity and stability development of many nanoparticle-based enhancement,Through in addition to this the apparent exercise, cost savings. Awe series have of multimetallic identified nanoparticle synthesisa methodspreliminary (e.g. efforts. with food and are widely used in food with AC160TS coreduction and thermal decomposition) have been used to prepare targeted multimetallic nanocrystals with specific extra and intracellular biodiagnostic and elementalhomogeneous compositions and size. These alloy methods, however,PtAuCu are usually nanoparticle system-specific and lack in generalizability. products. From in vivo and in vitro studies cantilever. Park Systems Announces 2019 Park AFMRecently, Scholar the Mirkin group reportedLiliang a novel synthesis Huang method, termed PhD scanning Northwestern probe block copolymer lithography University therapeutic tools. (SPBCL),as which a allowmoreed for theefficient synthesis of a library and of multimetallicstable nanoparticlesHER catalyst of up to five elements (Au, Ag, d) Corresponding Cu, Co, and Ni) by using a simple two-step thermal annealing treatment. This synthetic route forms a versatileHow platform do you use Park AFM in your of host intestinal epithelial or immune for studying the catalysis-related properties of the nanoparticles.In this work, by effectively utilizing SPBCL in overlaid Liliang Huang is from The Mirkin Research Group at Northwesterncombinationthan with densi thety University functionalcommercial theory (DFT)which calculations, Pt/C has catalyst.pioneered we introduced a novel the strategy use to of design nanoparticle andresearch? discover - cell responses to probiotic strains, it cost-effective HER electrocatalysts. Through this exercise, we have identified a homogeneous alloy PtAuCu topography, biomoleculeResearch conjugates summary as synthons in materials sciencenanoparticle and as athe more developmentefficient and stable HER of catalys manyt than the nanoparticle commercial Pt/C catalyst.-based extra-Park and intracellularAFM instrument is quite important has been reported that adhesion of biodiagnostic and therapeutic tools. for my research. I not only use it as a probiotic strains to the intestinal surface adhesion energy Hydrogen is widely used as a clean, multimetallic nanoparticle synthesis and the subsequent colonization of and force line Researchrenewable summary alternative to fossil fuels, instrument, but also employ it to the human gastrointestinal tract are profiles. while water electrolysis represents characterize the size and height of important prerequisites for probiotic Hydrogen is widely used as a clean, renewable alternative to fossil fuels, while water electrolysis represents an increasingly important method for the patterned polymer nanoreactor action [1]. This study looks into the an increasingly important method for industrial hydrogen manufacturing (~5% of the market). Currently, platinum is industrial hydrogen manufacturing (~5% features. Specifically, I synthesize extensively used as a hydrogen evolution reaction (HER)electrocatalyst for water electrolysis; however, its scarcity and topography and adhesion properties of of the market). Currently, platinum is nanoparticles through a process called those microorganisms to determine the high costlimits its practicality in electrolyzers. The key motivation of my graduate studies is focused on developing extensively used as a hydrogen evolution Fig. 1. (a) An SEM image of uniformly patterned polymer nanoreactor arrays synthesized with a modified AFM SPBCL, instrument. where polymer pen arrays were novel strategies to discover, design and fabricate(b) costAFM image-effective of the nanoreactor HER arrays. electrocatalysts. shape and form that adheres well to the adhesion force images were acquired three different surfaces identified in this Fig. 1. (a) An SEM image of uniformly patterned polymer reactionNanoparticles (HER)electrocatalyst are emerging for water as attractive HERIn an acidic electrocatalysts electrolyte, the catalyst hydrogen for bindingresearchers energy (HBE) isdue the sole to reaction their descriptor enhancedplaced for HER activityinto a modified AFM instrument colon by means of using commercially using the PinPoint Nanomechanical Mode. study: the cantilever tip (surface 1), the electrolysis; however, its scarcity and high activity andnanoreactor an optimal HER catalystarrays should synthesized have an HBE that with is neither a modified too strong nor AFM too weak. We first usedand density brought into contactwith a flat when compared to their bulk counterparts. Pt-based instrument.multimetallic (b) AFM nanoparticles image of the nanoreactor are particularly arrays. interesting because available probiotics and the PinPoint Images obtained were 256 x 256 pixels and bacteria (surface 2) and the silicon wafer alloyingcost limitsPt with practicality earth abundant in electrolyzers. transition metal The elements (e.g. Cu) is found to be favorable for activitysubstrate and stability to pattern uniform polymer nanomechanical mode of an atomic force 2 µm x 2 µm sizes. (surface 3). All three surfaces have different enhancement,key motivation in addition of my tograduate the apparent studies cost is savings. A series of multimetallic nanoparticle synthesis nanoreactors.methods (e.g. These nanoreactors microscopy (AFM) instrument from Park physicochemical properties: surface area, coreduction and thermal decomposition) have been usedIn an to acidic prepare electrolyte, targeted multimetallic the catalyst nanocrystals with specific focused on developing novel strategies hydrogen binding energy (HBE) is the sole can further be thermally treated to Systems. Result surface energy, surface roughness size and elementalto discover, compositions design and and fabricatesize. These cost- methods, however, are usually system-specific and lack in generalizability.produce nanoparticles. During the Recently, the Mirkin group reported a novel synthesisreaction method descriptor termed scanning for HER probe activity block and copolymer an lithography Figures 1a, b and c are the adhesion shape, which affect the adhesion force and effective HER electrocatalysts. nanoparticle synthesis process, I will Experimental (SPBCL), which allowed for the synthesis of a libraryoptimal of multimetallic HER catalyst nanoparticles should have of upan toHBE five elements (Au, Ag, energy, adhesion force and topography energy. also use Park AFM to characterize the Cu, Co, and Ni) by using a simple two-step thermal thatannealing is neither treatment. too strong This syntheticnor too weak. route forms a versatile platform To isolate probiotic bacteria, 1 mL samples images, respectively, of isolated for Nanoparticlesstudying the catalysis are emerging-related propertiesas attractive of the nanoparticles.We first usedIn density this work, functional by effectively theory utilizing SPBCLsize uniformity in of the patterned polymer of a commercial product were put into Streptococcus chains from a 10-5 dilution. Conclusion combinationHER electrocatalysts with density for functional researchers theory (DFT) calculations,(DFT) calculations we introduced to evaluate a novel the strategy HBE to designfeatures. and discover Furthermore, the height and microcentrifuge tubes and centrifuged Figure 1d shows the corresponding The test results show that probiotic costdue-effective to their HER enhanced electrocatalysts. activity when Through this exercise,for a series we have of multimetallic identified a homogeneous nanoparticles alloy PtAuCusize ratio information of the patterned (BioLab centrifuge) for 15 min at 10000 overlaid topography, adhesion energy and bacteria under study were less adhesive nanoparticlecompared as to a moretheir bulkefficient counterparts. and stable HER catalysandt identifiedthan the commercial PtAuNi and Pt/C PtAuCu catalyst. alloy polymer features obtained from AFM rpm to separate the biomass pellet. force line profiles. The adhesion energy to the Si cantilever tip compared to Pt-based multimetallic nanoparticles are nanoparticles as promising HER catalysts. measurements can also give me an idea The supernatant was discarded and the (Figure 1a) and adhesion force (Figure the Si substrate. This phenomenon particularly interesting because alloying Then SPBCL was used to accordingly of the hydrophobicity of the substrate, biomass was recovered in a test tube. 1b) behaved in a similar manner; smaller can be correlated with the adhesion of Pt with earth abundant transition metal synthesize these nanoparticles (Fig. 1), which is an important concern for this Serial dilutions (1 mL of biomass in 9 values were observed for the bacteria probiotic strains to the site of action, elements (e.g. Cu) is found to be favorable followed by characterization of their nanoparticle synthesis process. mL of sterile saline solution) from 10-1 compared with the substrate where they an important prerequisite for probiotic for activity and stability enhancement, catalytic properties towards HER. Through to 10-5 were performed [2]. From the were attached. action. We found from nanomechanical in addition to the apparent cost savings. this process, we confirmed PtAuCu alloy Why do you think Park AFM is a 10-5 dilutions, 0.1 mL drops were placed measurements that the adhesion force A series of multimetallic nanoparticle nanoparticles as excellent HER catalysts valuable tool for researchers? onto a silicon wafer chip (Ted Pella, Inc. The adhesion energy on the silicon wafer and adhesion energy are affected by the synthesis methods (e.g. coreduction and highlighted the phase structure Nanotechnology has provided additional 16007) and allowed to air dry. For bacteria chip was 400 aJ, but just 200 aJ on the physicochemical characteristics from each and thermal decomposition) have been as a key parameter in determining the opportunities for researchers to address characterization, a Park NX10 AFM from probiotic bacteria. Similar results were substrate. Therefore, adhesion force and used to prepare targeted multimetallic HER performance of the nanocatalysts, existing energy, environmental, and Park Systems was used; measurements obtained for the adhesion force (Figure adhesion energy values were lower when nanocrystals with specific elemental where the phase separation withinPtAuNi biological-related problems that are were performed in air using an AC160TS 1d); 20 nN for the bacteria but 45 nN on the the measurement was on the bacteria compositions and size. These methods, heterodimer particles (PtNi forms one difficult to be solved with conventional cantilever. PinPoint™ Nanomechanical silicon wafer chip and clearly indicates that compared to that done on the silicon wafer. however, are usually system-specific and bulk materials. Park AFM, as a flagship Mode from Park Systems can be used phase domain and Au forms another less force was required on the bacteria. References lack in generalizability. Recently, the Mirkin domain) results in poor HER catalytic AFM instrument, has enabled researchers to study surface topography as well as The isolated bacteria in air is observed [1] Saarela M et al.,Journal of Biotechnology. 2000; (84) group reported a novel synthesis method to obtain precise topographical determine quantitative nanomechanical 197-215. Fig. 1. (a) An SEM image of uniformly patterned polymeractivities. nanoreactor arrays synthesized with a modified AFM instrument. to be relatively less adhesive than that [2] Mendoza M AG et al., Revista Mexicana de Ingeniería (b) AFMtermed image scanning of the nanoreactorprobe block arrays. copolymer information about the nanostructures, properties (i.e., modulus, adhesion of the underlying Si substrate. Bacterial Química. 2017; 16(1): 159-168. [3] Park Systems’s PinPoint™ Nanomehcanical mode lithography (SPBCL), which allowed for Finally, a bulk synthetic method was which is highly important for force, adhesion energy) [3]. In this adhesion is based on physical interactions In an acidic electrolyte, the catalyst hydrogen binding energy (HBE) is the sole reaction descriptor for HER https://www.parksystems.com/index.php/en/park- the synthesis of a library of multimetallic used to scale up the discovered PtAuCu nanofabrication and its applications. study, topography, adhesion energy and between two or more surfaces. There were afm-modes/nanomechanical-modes?i=0 activity and an optimal HER catalyst should have an HBE that is neither too strong nor too weak. We first used density

24 NANOscientific www.nanoscientific.org NANOscientific 25 What are Programmed Knots and Knot Theory?

You can actually program the links SUPRAMOLECULAR MATERIALS MATTER to give specific catenated or knotted A model of a single- structures based on the degree of molecule car that CHEMISTRY, can advance across a Column Highlighting Topics complexation and ligand-to-metal NANOMACHINES, interaction such as it was popularized copper surface when AND AFM Presented in Dr. Advincula’s by Sauvage during the 1990s. You can electronically excited by Monthly Webinars on create metal-to-ligand interactions with an STM tip.

COLUMN 2 COLUMN Advancements in Material Science one metal, two metals, three metals, four metals, and five metals, by closing Credit: Courtesy of the ring, let’s say connecting A and B or Ben Feringa, co-winner Dr. Rigoberto Advincula, Professor, X and Y, you will end up actually with Nobel Prize a catenated structure of two rings by Macromolecular Science & Engineering Case Western Reserve University demetalation. On the other hand, if you take a NANOTECHNOLOGY REQUIRES Can you describe Supremolecular The ability to put this together to form bidentate ligand and complex two and tip and the assembly or adsorption the simplest one, the trefoil knot is THE USE OF TOOLS NEEDED Chemistry? larger structures with finite geometry metals within this ligand and close the of the supramolecular structures in flat based on a 3-1 structure. The question TO UNDERSTAND PHENOMENA such as a trefoil knot or a Borromean ring ring, you can actually demetalate that surfaces. AFM actually plays the key role is how can we prepare this and can When we talk about molecules, or Solomon link has been a fascination and form the simplest knot or a trefoil in observing some of these movement or we observe this indirectly and directly. AND MANIPULATE MATERIALS synthesizing new types of complexes, of a lot of organic chemistry aficionados, knot. What you can see here as you motion on what we call nanomachines Synthetically, we just extended the ALL THE WAY TO THE ATOMIC macromolecular systems that involve scientists, who would like to be the first go with an odd and even number of or molecular cars. catenated structures into this bidentate LEVEL. ATOMIC FORCE metal-to-ligand interaction or even to report this type of architecture using chelation, you can go from a cyclic to a ligand and the bi-functional ligand MICROSCOPY (AFM) IS ONE protein assemblies in enzymes, what these different building blocks. There’s knot, cyclic to a knot, cyclic to a knot, Nanocars, when adsorbed on flat was then closed and then finally, the OF THE MOST IMPORTANT is fascinating is that you can use the a whole world there of organic chemists and so on. What’s fascinating here is surfaces such as mica where the caprolactone was polymerized form a different types of non-covalent and who are fascinated with building this that this is a programmable method movement of the axle and the rod or polycaprolactone system. Of course, METHODS FOR PROBING AND covalent interactions to create larger supramolecular structures or even trying based on knot theory to create interlinks wheel and the tire rods show movement demetalation when unfolded should HARNESSING THE POTENTIAL molecules with varying complexity or to observe their formation of extended structures that are defined based on the over a particular space that can be give a trefoil knot. OF NANOTECHNOLOGY. structures that are beautiful and at the and higher ordered structures. template that they originated with. tracked by atomic force microscopy. same time functional. What opens Just to confirm that we can observe The Nobel Prize in Chemistry 2016 was the door for different types of modular What are Synthetic Strategies for This has to be designed properly or What is the Interest in Polymer this by UV-Vis spectroscopy, NMR, or awarded to Sauvage, Stoddart, and approaches in chemistry is that you Polymer Catenation? programmed properly in order to get the Physics about Molecular knots? even x-ray photoelectron spectroscopy Feringa for their work in supramolecular can take these building blocks and design cyclic structure or supramolecular to confirm the presence of copper and chemistry and it highlighted the assemble them in terms of different A basic strategy usually involves the use molecule. You can simulate or even The interesting thing is if knots are tin on the molecules showed that we need for nanomanipulation and geometries, taking molecular precursors of a more template-directed catenation calculate the type of interactions and formed in your DNA during replication, have a good correspondence with the probes to demonstrate stimulation into different architectures that then or binding whereas in the statistical the degree of interaction to result in that you’re probably be dead. The reason drone structures and the empirical response and motion to molecular can be complex, let’s say, in guest host catenation or threading, you don’t have particular geometry. Even higher orders is that cyclic structures or knots are proof. and nanomachines. AFM is one of systems that will allow you to look at that yield that allows you to isolate a of assembly including proteins, a double unnatural systems that can mess up GPC was used to look at the changes the few methods available to directly binding kinetics or self-assembly towards higher yields of specific cyclic structures helix can result in long range ordering your DNA or cause diseases. The in the hydrodynamic volumes. Let visualize and manipulate these nano- higher ordered structures. You have or catenation whereas by templating of these structures to result in rods or fortunate thing is the human body me emphasize that a ring structure objects by investigating topology a molecular approach to prepare the it, one can bias the system such that particle complexes such as micelles, has what we call DNA polymerases compared to a linear polymer will have and field response in flat surfaces building blocks that can then result into that particular precursor structure can vesicles, and nanoparticles. that actually correct these structures a lower hydrodynamic volume even and using specific cantilever-tip to higher complexity based on the synthesis be formed followed by the final step These are the building blocks to go and destroy them before they can do though they have the same molecular molecule interactions. AFM techniques of these building blocks with finite which is in this case ring closure. This from molecular to nanomolecular more harm. In polymer physics, knots weight. For example, here in this GPC based on contact and non-contact covalent structures, however, you can basic dichotomy between statistical and then mesoscopic. So for example and entanglements are a particular trace, you will see a linear polymer modes including scanning tunneling prepare different types of non-covalent and templated direction actually is the cyclodextrin, cucurbiturils, calixarines interest because chain entanglement as equivalent of a knotted polymer of microscopy (STM) as well as field- structures or complexation to build larger key towards higher yields or isolation of are rings that are hydrophobic inside and observed with high molecular weight the same molecular weight but the responsive methods have enabled macromolecules or supramolecular specific geometries based on molecular hydrophilic outside, therefore, making polymers result in changes in the knotted polymer has a higher retention quantitative and visualized experiments structures that then can have function for bias. That is why templates such as them efficient complexing agents that thermo-mechanical, physical, chemical volume indicating that even though to correlate with the dynamics of recognition, transport and catalysis. transitional metal, donor-acceptor, can render organic molecules more properties of polymers in solution or the molecular weight is the same, the macromolecular and supramolecular hydrogen bonding, or other types of soluble in aqueous or more polar melt or other real logical parameters hydrodynamic volume of the knotted chemist. What are Supramolecular Chemistry ligand complexation is quite effective solvents. or even reptation to tubes or narrow macromolecule is lower or smaller. Molecule Knots? in locking or preparing this interlock geometries or channels. The proof is on the AFM. Actually, this This column summarizes a webinar structure where the final step can Can AFM be used to observe was the first report of a trefoil knot on AFM imaging of knotted polymers. You can actually have these intricate be used to close the ring or prepare nanomachines or molecular cars? Can you explain Knotty Polymers by a synthetic polycaprolactone that was This is a summary of the complete cyclic structures, polycycles, macrocycles, different types of extended structures Ring-Expansion Strategy observed on mica and then upon webinar given by Dr. Advincula. To different types of order where the building such as tubes, calixarene rings, AFM is a possible tool to actually closer examination of that adsorbed view this webinar and other webinars, of these structures can be achieved chalice-type of structures, or different visualize this supramolecular structure It is possible to make a knotty polymer macromolecule indeed the trefoil knot go to: www.parksystems.com/ through ion complexation, hydrogen geometries that are geometrically based on the interaction of the cantilever by ring-expansion strategy. A true knot, structure was confirmed. supramolecular bonding, or donor-acceptor systems. feasible.

26 NANOscientific www.nano-scientific.org www.nanoscientific.org NANOscientific 27