The Center for Nanoscale Materials (CNM) hosts biweekly colloquia that provide a forum for topical multidisciplinary talks in areas of interest to the CNM and that offer a mechanism for fostering interactions with potential facility users.
When: Alternate Wednesdays at 11:00 a.m.
Where: Argonne National Laboratory, Colloquiums present in 2 formats, VIRTUAL via Zoom and HYBRID (in-person (Building 440, Room A105/106) and Zoom. See Agenda for information.
Colloquium Committee Members: Xiao-Min Lin (Chair), Pierre Darancet, Ralu Divan, Xuedan Ma, Elena Rozhkova, Jianguo Wen
2023 Schedule
DATE | |
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January 30, 2023 | “Following and Controlling Formation and Function of Bottom-up Assembled Nanomaterials”, Naomi Ginsberg, UC Berkeley - College of Chemistry, Host: Richard Schaller, ABSTRACT |
February 1, 2023 | “Functional Bio-enabled Nanomaterials: from Adaptive Photonic Materials to Actuating Flexible Magnets”, Vladimir V. Tsukruk, Georgia Institute of Technology, Host: Elena Rozhkova, ABSTRACT |
February 15, 2023 | “Mixed-Dimensional Heterostructures for Electronic and Energy Technologies”, Mark Hersam, Northwestern University, Host: Nathan Guisinger, ABSTRACT |
March 1, 2023 | Yun Hang Hu, Michigan Technological University, Host: Gary Wiederrecht |
March 15, 2023 | Lilo D. Pozzo, University of Washington, Host: Progna Banerjee |
April 26, 2023 | Shijing Sun, Toyota Research Institute, Host: Maria Chan |
May 10, 2023 | Pramod Reddy, University of Michigan, Host; Muchuan Hua |
May 24, 2023 VIRTUAL |
Ido Kaminer, Technion Israel Institute of Technology, Host:Thomas Gage |
May 31, 2023 | Jeremy Baumberg, University of Cambridge, UK, Host: Dafei Jin |
June 7, 2023 | Ling-Jian Meng, University of Illinois at Urbana-Champaign, Host: Elena Rozhkova |
June 21, 2023 | Stephanie Brock, Wayne State University. Host: Elena Shevchenko |
July 5, 2023 | |
July 19, 2023 | |
Aug. 2, 2023 | |
Aug. 16, 2023 | |
Aug. 30, 2023 | |
Sep. 13, 2023 | Hongyou Fan, Sandia National Laboratory, Host: Elena Shevchenko |
Recent Colloquia
January 4, 2023 | Semiconductor-based biological modulation interfaces at all length scales, Bozhi, Tian, University of Chicago. Host: Xiao-Min Lin. ABSTRACT |
December 7, 2022 | “Intervention of bioprocesses by nano/micro-fabrication”, Rong Wang, Illinois Institute of Technology, Host: Ralu Divan. ABSTRACT |
November 11, 2022 FRIDAY |
“Predicting Defect Topologies in 2D Materials and their Effect on Molecular and Ionic Transport.”, Ananth G. Rajan, Indian Institute of Science (IISc), Bengaluru, Host: Subramanian Sankaranarayanan. ABSTRACT |
November 9, 2022 | Dynamics and Emergent Complexity in Functional Nanocrystals and Nanocrystal Superstructures, Xingchen Ye, Indiana University, Host: Ben Diroll. ABSTRACT |
October 26, 2022 | “Nanoscale electron paramagnetic resonance and quantum opto-mechanics with diamond spin qubits”, Gurudev Dutt, University of Pittsburgh, Host: Jeff Guest. ABSTRACT |
September 14, 2022 | “A generalized memory function based on recoverable strain and its relation to nanoscale structure”. Simon Rogers, University of Illinois, Host: Xiao-Min Lin. ABSTRACT |
August 31, 2022 | “Multifunctional van der Waals Quantum Materials”, Xavier Roy, Columbia University, Host: Elena Shevchenko. ABSTRACT |
July 29, 2022 11:00 am |
“Exciton Physics and Cavity Quantum Electrodynamics in air-suspended Carbon NanoTubes”. Yuichiro Kato, RIKEN Japan, Host: Xuedan Ma, ABSTRACT, HYBRID Event |
July 6, 2022 | “Natural and Synthetic Microbial Protein Nanowires for Bioelectronic Interfaces”, Nikhil Malvankar, Yale University, Host: Chris Fry, ABSTRACT |
June 8, 2022 | Rapid flow synthesis of proteins and peptides, Bradley Pentelute, Massachusetts Institute of Technology, Host: Chris Fry, ABSTRACT |
May 25, 2022 10:00 am |
Photon Correlation as a Resource in Microscopy and Spectroscopy, Dan Oron, Weizmann Institute of Science, Host Xuedan Ma. ABSTRACT |
Apr 27, 2022 | Materials Chemstry for Optoelectronics and for Decarbonization, Ted Sargent, University of Toronto, Host: Elena Shevchenko, ABSTRACT |
Apr. 13, 2022 | Ernst Meyer, University of Basel, Host: Saw Hla. ABSTRACT |
May 30, 2022 | Spins, Bits, and Flips: Essentials for High-Density Magnetic Random-Access Memory, Tiffany Santos, Host: Xiao-Min Lin and Valentine Novosad. ABSTRACT |
POSTPONED Mar 30, 2022 |
Mobile Optical Excitations in Two-Divensional Materials, Alexey Chernikov, University of Regensburg (Germany), Host: Darien Morrow. ABSTRACT |
Mar 2, 2022 | Macroscope Materials from Nanoparticle Assembly, Robert Macfarlane, MIT (Department of Materials Science and Engineering), Host: Elena Shevchenko, ABSTRACT |
Feb 16, 2022 | Synthesis and Applications of Colloidal Nanorod Heterostuctures, Moonsub Shim, UIUC, Host: Xiao-Min Lin, ABSTRACT |
Feb 2, 2022 Time: 1:30 pm |
First principles modeling of materials: novel electronics, ultra-low stiffness metals and open cloud computing in nanoHUB, Alejandro H. Strachan, Purdue University, Host: Subramanian Sankaranarayanan ABSTRACT |
Jan 19, 2022 | Bioapplication of magnetic nanowires; barcodes, heaters, biocomposites, Bethanie Stadler, University of Minnesota - Twin Cities. Host: Thomas Gage. ABSTRACT |
Jan. 5, 2022 | Towards the elucidation of the mechanism of synthesis of zeolites, Valeria Molinero, University of Utah, Host: Subramanian Sankaranarayanan. ABSTRACT |
Dec 8, 2021 | Operating quantum states in a magnetic molecule, Wolfgang Wernsdorfer, Karlsruhe Institute of Technology, Host: Dafei Jin. ABSTRACT |
Oct. 27, 2021 | Optically-active systems at the atomic scale, Jeffrey Guest, Quantum and Energy Materials, Argonne National Laboratory, Host: Xiao-Min Lin. ABSTRACT |
Oct. 13, 2021 | Quantum Diamond Sensors, Ronald L. Walsworth, University of Maryland, Host: Elena Rozhkova. ABSTRACT |
Sept. 29, 2021 | Terahertz Quantum Cascade Lasers Reaching for Room Temperature Operation, Jerome Faist, ETH Zurich, Host: Benjamin Diroll. ABSTRACT |
Sept. 15, 2021 | Imaging glass dynamics and excited state dynamics on the sub-nm scale, Martin Gruebele, University of Illinois at Urbana-Champaign, Sarah Wieghold, ABSTRACT |
Sept. 1, 2021 | Manipulating Nanoscale Interactions at Nano-Bio Interface, Elena Rozhkova, Nanophotonics and Biofunctional Structures, Argonne National Laboratory, Host: Elena Shevchenko. ABSTRACT |
Aug. 18, 2021 | Renaissance of Megaelectronvolt Electron Scattering, Xijie Wang, SLAC National Accelerator Laboratory, Host: Jianguo Wen, ABSTRACT |
Aug. 4, 2021 | Hexagonal Boron Nitride - emerging platform for Quantum Photonics, Igor Aharonovich, University of Technology Sydney, Xuedan Ma. ABSTRACT |
July 30, 2021 10:00 am |
NST Director’s Special Colloquium Bioinspired Polymer Microelectronics, Sihong Wang, Pritzker School of Molecular Engineering, University of Chicago. Host: Ilke Arslan. ABSTRACT |
July 21, 2021 | Electronic Dynamics Underlying Molecular and Nanoplasmonic Light Harvesting Studied by Ultrafast X-Ray Photoelectron Spectroscopy, Oliver Gessner, Lawrence Berkley National Laboratory, Host: Gary Wiederrecht, Abstract |
July 14, 2021 | “Developing Quantum Photon Sources from Low-dimensional Semiconductor Materials”, Xuedan Ma, Nanophotonics and Biofunctional Structures, Argonne National Laboratory, Host: Pierre Darancet. ABSTRACT |
June 23, 2021 | Accelerating Exploratory Materials Synthesis with Data, Machine Learning, and Robots, Joshua Schrier, Fordham University, Host: Pierre Darancet. Abstract |
June 9, 2021 | Single and Multicomponent Superlattice Structures with Perovskite Nanocrystals; Structural Diversity and Collective Emission, Maksym Kovalenko, UTH Zurich, Host: Elena Shevchenko. ABSTRACT |
May 26, 2021 | Quantum State Engineering with Integrated Nonlinear Photonics, Linran Fan, University of Arizona, Host: Xu Han. ABSTRACT |
April 28, 2021 | Exotic Interactions with Light and Sound in Metamaterials with Broken Symmetries, Andrea Alu, City University of New York (CUNY), Host: Pierre Darancet, ABSTRACT |
April 14, 2021 | Robot-accelerated Materials Discovery: From Perovskites to Photon Avalanches, Emory Chan, Lawrence Berkeley National Laboratory, Host: Jie Xu. ABSTRACT |
Mar. 31, 2021 | On-surface Reactions and Single Molecule Charge Transitions Controlled by Atomic Manipulation, Leo Gross, IBM Zurich, Host: Saw-Wai Hla, ABSTRACT |
Mar. 3, 2021 | Sara Schkrabak, Indiana University Bloomington, Host: Elena Shevchenko, ABSTRACT |
Feb. 17, 2021 | Zeger Hens, Ghent University, Host: Richard Schaller, ABSTRACT |
Feb. 3, 2021 | Liangbin Hu, University of Maryland, Host: Yuzi Liu |
Jan. 20, 2021 | “Chiral Plasmonic Nanomaterials by Templated Growth and Assembly of Gold Nanocrystals”, Luis M. Liz-Marzan, CIC biomaGUNE, Spain, Host: Xiao-Min Lin, ABSTRACT |
Jan 6, 2021 | Vanessa Wood, Eidgenossische Technische Hochschule (ETH) Zurich, Host: Benjamin Diroll, ABSTRACT |
Dec. 9, 2020 | Ou Chen, Brown University. Host: Yuzi Liu ABSTRACT |
Oct. 28, 2020 | Screening the Space of Inorganic Materials for Function Using Data Tabulation and Computation, Ram Seshadri, University of California Santa Barbara, Host: Arun K. M. Kanakkithodi. ABSTRACT |
Oct. 14, 2020 | The Rise of MXenes, Yury Gogotsi, Drexel University, Host: Elena Rozhkova. ABSTRACT |
Sep. 30, 2020 | The Surprising World of Complex Spin Structures, Matthias Bode, Universitat Wurzburg, Host: Jeffrey Guest. ABSTRACT |
Sep. 16, 2020 | Self-assembly of Colloidal Diamond for Photonics, David J. Pine, New York University, Host: Xiao-Min Lin, ABSTRACT |
Sep. 2, 2020 | Primordial Enzymes Through Protein Design, Vikas Nanda, Rutgers, Host: Chris Fry, ABSTRACT |
Aug 19, 2020 | Conversion-Type Lithium-Ion Materials and Ceramic Separators for Next Generation of Cheaper, Safer, and Lighter Rechargeable Batteries, Gleb Yushin, Georgia Tech. Host: Elena Shevchenko. ABSTRACT |
Aug. 5, s2020 | Topological Photonics at the Nanoscale, Bo Zhen, University of Pennsylvania, Host: Dafei Jin. ABSTRACT |
July 22, 2020 | Next Level Layered Materials, Joshua E. Goldberger, Ohio State, Host: Xuedan Ma. ABSTRACT |
May 13, 2020 | POSTPONED: Vikas Nanda, Rutgers University, Host: Christopher Fry |
April 29, 2020 | POSTPONED: Valentine Novosad, Materials Science Division, Argonne National Laboratory. Host: Xiao-Min Lin |
April 1, 2020 | POSTPONED: Josh Goldberger, Ohio State University, Host: Xuedan Ma |
May 18, 2020 | CANCELED - |
Feb. 19, 2020 | Biologically Germane Sensing with Aptamer-Field-Effect Transistors, Anne Andrews, University of California, Host: Elena Rozhkova. ABSTRACT |
Feb 5, 2020 | The Unexpected Role of Carbon in Photocatalytic Nitrogen Fixation by Titania Catalysts, Andrew J. Medford, Georgia Institute of Technology, Host: Arun Kumar Mannodi Kanakkithodi. ABSTRACT |
Jan. 22, 2020 | Designer Electronic States in Van der Waals Heterostructures, Brian LeRoy, Department of Physics, University of Arizona. Host: Jeff Guest. ABSTRACT |
Jan. 8, 2020 | Making Printable Flexible Electronics a Reality. Polymers, Heterojunctions, Amorphous Oxides/ Alloys, and Solar Cells. Tobin Marks, Northwestern University, Host: Pierre Darancet. ABSTRACT |
MONDAY Nov 25, 2019 |
Designing Inorganic Nanomaterials for Medical and Energy Applications, Taeghwen Hyeon, School of Chemical and Biological Engineering, Director of IBS Nanoparticle Research Center, Seoul National University, Host: Elena Shevchenko ABSTRACT |
Nov 13, 2019 | Quantum Information Processing with Bosonic Modes, Liang Jiang, University of Chicago - PME, Host: Xufeng Zhang ABSTRACT |
Oct 30, 2019 | Electronics for the Next 50 Years, Qing Cao, University of Illinois at Urbana-Champaign. Host: Xuedan Ma ABSTRACT |
Oct. 16, 2019 | Anomalies in Ambient and Supercooled Water: Is There a Second Critical Point Lurking Nearby?, James Skinner, Crown Family Professor of Molecular Engineering, University of Chicago. Host: Xiao-Min Lin ABSTRACT |
Oct. 2, 2019 | Bridging the Gap between Molecules and Nanoparticles, Eugenia Kumacheva, Department of Chemistry, University of Toronto. Host: Elena Shevchenko. ABSTRACT |
Sep. 18, 2019 | Thermal Relaxation of Electrons in Semiconductors and Nanomaterials, Pierre Darancet, Theory and Modeling group, Nanoscience and Technology division, Argonne National Laboratory. Host: Subramanian Sankaranaryanan. ABSTRACT |
Sep. 4, 2019 | Nanotechnology in the Oilfield, Dr. John Stevens, Baker Hughes, Host: Xiao-Min Lin. ABSTRACT |
Aug. 21, 2019 | Functional Materials: Potential and Promise, M. Ishaque Khan, Illinois Institute of Technology, Host: Ralu Divan ABSTRACT |
Aug. 7, 2019 | Quantum Optomechanics and Engineered Dissipation, Aashish Clerk, Institute for Molecular Engineering, University of Chicago. Host: Matthew Otten . ABSTRACT |
July 24, 2019 | Nanotechnology: From Graphene to Molecular Nanomachines, James Tour, Rice University, Host: Saw W. Hla, ABSTRACT |
Jun. 26, 2019 | Data-driven Design of Self-assebling Photonic Crystals and Machine Learning of Latent Space Molecular Simulators, Andrew Ferguson, University of Chicago, Host: Subramanian Sankaranarayanan ABSTRACT |
May 29, 2019 | Maxwellian Phases of Matter, Zubin Jacob, Purdue University, Host: Peijun Guo, ABSTRACT |
May 15, 2019 | Computational Modeling and Screening of Semiconductor Electrodes for Solar-to Fuel Conversion, Ismaila Dabo, Penn State, Host: Pierre Darancet, ABSTRACT |
May 1, 2019 | Manifestation of Spin-Couplings in Computational Molecular Spectroscopies, Xiaosong Li, Harry and Catherine Jaynne Boand Endowed Professor Chemistry, University of Washington, Host: Xuedan Ma, ABSTRACT |
Apr. 17, 2019 | Skin in the Game: Photoproperties of DNA and Melanin Biopolymers Revealed by Ultrafast Laser Spectroscopy, Bern Kohler, Ohio State University, Host: Gary Wiederrecht, ABSTRACT |
Apr. 11, 2019 Special Colloquium Thursday |
CANCELED - Stimulated Emission by Colloidal Quantum Dots, Zeger Hens, Ghent University, Host: Richard Schaller, ABSTRACT - CANCELED |
Mar. 20, 2019 | Crafting Light at the Nanoscale with 2D Materials and Metasurfaces, Alexander High, University of Chicago, Host: Jeff Guest, ABSTRACT |
Feb. 20, 2019 | Fundamental Properties and Device Prospective of Emerging two-Dimensional Materials, Han Wang, University of Southern California, Host: Xu Zhang, ABSTRACT |
Feb. 6, 2019 | CANCELED - Electron Photoemission from Diamond and Integration of Plasmonic Nanoparticles into Diamond, Robert J. Hamers, University of Wisconsin - Madison, Host: Xiao-Min Lin, CANCELED |
Jan. 16, 2019 | Juejun Hu, Massachusetts Institute of Technology (MIT), Host: Peijun Guo. ABSTRACT |
Jan. 9, 2019 | Jennifer Ann Hollingsworth, Los Alamos National Laboratory, Host: Elena Shevchenko, ABSTRACT |
Dec. 12, 2018 11:00 a.m. Bldg. 402 GALLERY |
From Band Gaps to Bound Excitons: Disentangling Optical Transitions and Localized emitters in TMDCs Even at Nanoscale Dimensions, P. James Schuck, Department of Mechanical Engineering, Columbia University, Host: Pierre Darancet ABSTRACT |
Nov. 14, 2018 | Revealing the Structure and Function of Membrane Proteins Through Nanotechnology, Stephen G. Sligar, University of Illinois, Host: Elena Rozhkova, ABSTRACT |
Oct. 31, 2018 | Nanoengineering and Integration of Materials with Unique Functionalities - Oxide-Oxide Nanocomposites and Beyond, Haiyan Wang, Purdue University, Host: Joyce (Jie) Wang and Xuedan Ma, ABSTRACT |
Oct 17, 2018 | Synthesis and Photophysical Properties of Strongly Confined Cesium Lead Halide Perovskite Quantum Dots, Dong Hee Son, Texas A&M University (TAMU), Host: Xuedan Ma. ABSTRACT |
Oct. 3, 2018 | Leverage Physiology for Bioresponsive Drug Delivery, Zhen Gu, University of California Los Angeles (UCLA), Host: Zhaowei Chen. ABSTRACT |
Sep. 19, 2018 | Incorporating Metastability Into Materials Design and Discovery, Stephan Lany, National Renewable Energy Laboratory (NREL), Host: Maria Chan. ABSTRACT |
Sep. 5, 2018 | Developing Hybrid Nanostructures for Energy and Biomedical Applications, Dongling Ma, Institut National de la Recherche Scientifiue (INRS), Host: Gary Wiederrecht. ABSTRACT |
Aug. 8, 2018 |
Atomic Origami: A Technology Platform for Nanoscale Machines, Sensors, and Robots, Itai Cohens, Cornell University, Host: Xiao-Min Lin What would we be able to do if we could build cell-scale machines that sense, interact, and control their micro environment? Can we develop a Moore’s law for machines and robots? In Richard Feynman’s classic talk “There’s Plenty of Room at the Bottom” he foretold of the coming revolution in the miniaturization of electronics components. This vision is largely being achieved and pushed to its ultimate limit as Moore’s Law comes to an end. In this same lecture, Feynman also points to the possibilities that would be opened by the miniaturization of machines. This vision, while far from being realized, is equally as tantalizing. For example, even achieving miniaturization to micron length scales would open the door to machines that can interface with biological organisms through biochemical interactions, as well as machines that self-organize into superstructures with mechanical, optical, and wetting properties that can be altered in real time. If these machines can be interfaced with electronics, then at the 10’s of micron scale alone, semiconductor devices are small enough that we could put the computational power of the spaceship Voyager onto a machine that could be injected into the body. Such robots could have on board detectors, power sources, and processors that enable them to make decisions based on their local environment allowing them to be completely untethered from the outside world.In this talk I will describe the work our collaboration is doing to develop a new platform for the construction of micron sized origami machines that change shape in fractions of a second in response to environmental stimuli. The enabling technologies behind our machines are graphene-glass and graphene-platinum bimorphs. These ultra-thin bimorphs bend to micron radii of curvature in response to small strain differentials. By patterning thick rigid panels on top of bimorphs, we localize bending to the unpatterned regions to produce folds. Using panels and bimorphs, we can scale down existing origami patterns to produce a wide range of machines. These machines can sense their environments, respond, and perform useful functions on time and length scales comparable to microscale biological organisms. With the incorporation of electronic, photonic, and chemical payloads, these basic elements will become a powerful platform for robotics at the micron scale. As such, I will close by offering a few forward looking proposals to use these machines as basic programmable elements for the assembly of multifunctional materials and surfaces with tunable mechanical, optical, hydrophilic properties. |
July 25, 2018 |
Epitaxial Nanocomposite: A Pathway for Tunable Functionalities, Quanxi Jia, State University of New York (SUNY), Host: Liliana Stan Epitaxial nanocomposites provide a pathway to produce tunable and improved properties that are often not accessible from the individual constituents. Over the years, new discoveries and major advances have been made to synthesize epitaxial nanocomposite films and to gain fundamental understanding of their physical properties such as ferromagnetism ferroelectricity, and multiferroicity. In this talk, I will overview our effort to understand, exploit, and control competing interactions of a range of epitaxial nanocomposite metal oxide films. Using both ferroelectric and ferromagnetic oxides as model systems, we have illustrated that certain physical properties of the materials could be systematically tuned by controlling the strain state of the epitaxial nanocomposite films. Our phase field simulations have suggested that the ultimate strain in the interested phase is related to the vertical interfacial area and interfacial dislocation density of the epitaxial nanocomposite films. |
Jun. 27, 2018 | Extending The Scale and Enhancing the Yield of Self-Assembled Structures, James Alexander Liddle, National Institute of Standards and Technology (NIST), Host: Ralu Divan Self-assembly is ubiquitous in biological systems, but remains challenging for synthetic structures. These typically form under diffusion-limited, near-equilibrium conditions. DNA-mediated self-assembly is a powerful method with which to build multi-functional, molecularly-addressable nanostructures of arbitrary shape. While there have been many recent developments in DNA nanostructure fabrication that have expanded the design space, fabrication based on DNA alone can suffer from low yields and is hampered by the need to strike a balance between size and mechanical rigidity.1,2 Despite recent efforts,3 typical assembly protocols, employing large numbers of discrete components, offer little control over the assembly pathway, limiting structure size, complexity, and yield. We have been working to both understand the factors that limit the yield of self-assembled structures, and to devise approaches to overcome them. In this talk, I will discuss our attempts to build a simple, but predictive model, that describes the process of forming a single fold in a DNA origami structure. Using this model, we show that yield decreases exponentially as a function of the number of discrete components used to assemble a structure. To circumvent this limit, we have developed a two-stage, hierarchical self-assembly process, to create large structures with high yield.4 Our process employs a limited number of discrete, sequence-specific element to shape the structure at the nanoscale and control the large-scale geometry. A generic building block – a DNA binding protein, RecA – rigidifies the structure without requiring any unnecessary information to be added to the system. Expanding the self-assembly toolbox by blending sequence-specific and structure-specific elements, enables us to make micrometer-scale, rigid, molecularly-addressable structures. More generally, our results indicate that the scale of finite-size self-assembling systems can be increased by minimizing the number of unique components and instead relying on generic components to construct a framework that supports the functional units. 1 Murugan, A., Zou, J. & Brenner, M. P. Undesired usage and the robust self-assembly of heterogeneous structures. Nat. Commun. 6, 6203, doi:10.1038/ncomms7203 (2015). 2 Schiffels, D., Liedl, T. & Fygenson, D. K. Nanoscale structure and microscale stiffness of DNA nanotubes. ACS Nano 7, 6700-6710, doi:10.1021/nn401362p (2013). 3 Dunn, K. E. et al. Guiding the folding pathway of DNA origami. Nature, doi:10.1038/nature14860 (2015). 4 Schiffels, D, Szalai, V. A., Liddle, J. A., Molecular Precision at Micrometer Length Scales: Hierarchical Assembly of DNA–Protein Nanostructures, ACS Nano, 11, 6623, (2017)Jul. 13, 2018 |
Jun. 13, 2018 | Overcoming Materials Science Roadblocks to Reach the Next Frontiers of Carbon Nanoelectronics, Water Separation, and Beyond, Mike Arnold, Dept. of Materials Science and Engineering, University of Wisconsin-Madison, Host: Nathan Guisinger My research addresses fundamental challenges in controlling the growth, processing, ordering, and heterogeneity of nanomaterials and in understanding phenomena beyond the scale of single nanostructures – that must be overcome to exploit nanomaterials in technology. In this seminar, I will present on 3 recent advances from my laboratory: (1) We have pioneered a scalable approach for assembling parallel arrays of ultrahigh purity semiconducting nanotubes. This approach has allowed us to create carbon nanotube field effect transistors (FETs) with current density that exceeds Si and GaAs, for the first time, which has been a goal of the nanoelectronics field for 20+ years. (2) We have discovered how to drive graphene crystal growth on Ge(001) surfaces with a giant anisotropy. This giant anisotropy is remarkable because it enables the rational synthesis of narrow, long, smooth, and oriented nanoribbons of graphene that are semiconducting whereas unconfined graphene is typically a semimetal. This result opens up the possibility of realizing hybrid carbon nanoelectronics directly on conventional group IV or III-V semiconductor wafer substrates. (3) Laminates of graphene oxide nanosheets have been shown to exhibit high water permeance and salt rejection. We have used experiments and modeling to show that the water transport pathways through such laminates are not as expected. This work has implications in extending Moore’s Law, creating ultra-low energy logic circuits, developing higher bandwidth RF communication devices, and realizing next-generation water separation membranes. |
May 30, 2018 | “Quantum-Sized” Metal Nanoparticles for Photochemical Energy Conversion, Yugang Sun, Temple University. Host: Gary Wiederrecht Generation of hot carriers in transition metal catalysts through photoexcitation has been demonstrated to be a promising approach capable of significantly lowering activation temperature of the catalysts, which could have a widespread impact on substantially reducing the current energy demands and improving the selectivity of heterogeneous catalysis. Plasmonic nanoparticles made of Au, Ag, Cu, and Al are recently focused because they can actively absorb light at the corresponding surface plasmon resonance (SPR) frequencies, which are usually in the visible spectral region. The high optical absorptions lead to the generation of hot carriers in plasmonic nanoparticles, on which the hot carriers can directly drive chemical transformations. Despite the promise, plasmonic metal nanoparticles are not useful catalysts for a wide range of important reactions. In contrast, platinum-group metals (PGMs) such as Pt, Pd, Ru or Rh are excellent catalytic materials but exhibit SPR in the ultraviolet (UV) spectral region, which represents a significant disadvantage for photocatalysis due to the poor overlap with the solar spectrum. Although increasing size of PGM nanoparticles shifts SPR absorption to the red, it increases cost and reduces surface area and thus catalytic activity. Moreover, increasing the size of metal nanocrystals significantly reduces the yield of hot electron generation, lowering the efficiency of photochemical energy conversion. In this presentation, a new light absorption model will be discussed to demonstrate a transformative way to enhance optical absorption in small PGM nanoparticles in the visible spectral region by adjusting their dielectric environment instead of changing their size. In this model, the “quantum-sized” metal nanocrystals are attached to surfaces of transparent silica spheres, which can support a variety of dielectric scattering resonances (e.g., Fabry-Perot or Whispering Gallery modes depending on the size of silica spheres) capable of creating strong electric fields near the silica surface. The intensified nearfields can dramatically enhance the absorption cross-section of the metal nanocrystals, which are on the silica surface, thus improving the yield of “hot electrons” in the metal nanocrystals. This new model provides a unique opportunity to efficiently generate hot carriers in the PMG metal nanoparticles upon excitation of solar energy. |
May 16, 2018 | First Glimpse of a New Type of Two-Dimensional Crystals, Gong Gu, University of Tennessee, Host: Lifen Wang Traditional and new mainstream semiconductors are all sp3-coordinated crystals, including III-V, IV-IV, and, to a lesser extent, II-VI compounds, which are collectively referred to as octet compounds. Among octet compounds that exist in sp3-coordinated polymorphs, only boron nitride is known to exist also in sp2-coordinated forms, the most common of which is hexagonal BN (h-BN). Given the tremendous interest in two-dimensional (2D) crystals, a natural question is whether h-BN-like polymorphs can exist for at least some octet compounds other than BN. A theoretical study [1], based on an energetic consideration, predicted that each cation-anion bilayer in a wurtzite {0001} film would collapse into a planar, h-BN-like structure if and only if the film thickness is below a certain threshold. This transformation to the nonpolar structure is deemed a new stabilization mechanism for the otherwise polar crystals to avert the polar field in the ultra-thin limit [1]; a multitude of known mechanisms counter the would-be catastrophic divergence of potential due to the polar field for bulk crystals [2,3]. While the h-BN-like ultra-thin films were hailed as “precursors to wurtzite films,” experimental evidences have been illusive despite efforts to grow ultra-thin films [4,5]. This talk presents the discovery of h-BeO, the h-BN-like form of BeO, made in a serendipitous experiment at CNM. Nanocrystals of BeO formed in graphene-sealed liquid cells were identified by HRTEM and EELS. Since h-BeO and the usual wurtzite BeO (w-BeO) have nearly identical basal plane lattice constants, we resorted to the “fine structure” of EELS, or energy loss near edge structure (ELNES), to show the sp2 electron configuration. Furthermore, we measured h-BeO thicknesses significantly larger than the thermodynamic threshold above which w-BeO is more stable. I will explain why this can be achieved, as well as why previous attempts did not lead to h-BN-like films. Our theoretical work further shows that the h-BN-like thin films of the octet compounds with wurtzite bulks are not so much like h-BN. They constitute a new type of 2D materials, of which we just had a first glimpse. [1] C. L. Freeman et al, Graphitic nanofilms as precursors to wurtzite films: theory, Phys. Rev. Lett. 96, 066102 (2006). [2] C. Noguera, Polar oxide surfaces, J. Phys. Condens. Matter 12, R367 (2000). [3] A. Wander et al, Stability of polar oxide surfaces, Phys. Rev. Lett. 86, 3811 (2001). [4] Tusche et al, Observation of depolarized ZnO(0001) monolayers: formation of unreconstructed planar sheets, Phys. Rev. Lett. 99, 026102 (2007). [5] Lee et al, Tunable lattice constant and band gap of single- and few-layer ZnO, J. Phys Chem. Lett. 7, 1335 (2016). |
May 2, 2018 |
“Multimodal Microscopy Applied to Emerging Energy materials: Perovskite Solar Cells”, David S. Ginger, University of Washington, Host: Pierre Darancet From halide perovskite solar cells, to new polymer electrolytes for batteries, many emerging materials being explored for solar energy harvesting and storage show performance that depends sensitively on nanoscale structure. Rapid advances in the capability and accessibility of scanning probe microscopy methods have made it possible to study processing/structure/function relationships ranging from photocurrent collection, to ion uptake, to photocarrier lifetimes with resolutions on the scale of tens of nanometers or better in these materials. Importantly, such scanning probe methods offer the potential to combine measurements of local structure with local function, and they can be implemented to study materials in situ or devices in operando to better understand how materials evolve in time in response to an external stimulus or environmental perturbation. This talk highlights recent advances in the development and application of both scanning probe and optical microscopy methods to help address such questions while filling key gaps between the capabilities of conventional electron microscopy and newer super-resolution optical methods, with a specific focus on perovskite semiconductors. This talk will emphasize the application of multimodal microscopy to characterize perovskite solar cells, and discuss how these insights led us to surface passivation schemes that can achieve 96% of the Shockley-Queisser quasi-Fermi level splitting in these materials. |
Apr. 18, 2018 |
Theory and Practice of Nanoparticle Self Assembly, Nicholas A. Kotov, University of Michigan. Host: Gleiciani de Queiros Silveira |
Feb. 21, 2018 |
“Emerging Materials for Nanophotonics and Plasmonics”, Alexandra Boltasseva, Purdue University, Host: Gary Wiederrecht The fields of nanophotonics and plasmonics have taught us unprecedented ways to control the flow light at the nanometer scale, unfolding new optical phenomena and redefining centuries-old optical elements. As we continue to transfer the recent advances into applications, the development of new material platforms has become one of the centerpieces in the field of nanophotonics. In this presentation, I will discuss emerging material platforms including transparent conducting oxides, transition metal nitrides, oxides and carbides as well as two- and quasi-two-dimensional materials for future practical optical components across the fields of on-chip optics and optoelectronics, sensing, spectroscopy and energy conversion. |
Feb. 7, 2018 |
“Quantum Dynamics of Confined Molecules”, Pierre-Nicholas Roy, University of Waterloo, Host: Stephen Gray Molecular assemblies are often described using classical concepts and simulated using Newtonian dynamics or Classical Monte Carlo methods. At low temperatures, this classical description fails to capture the nature of the dynamics of molecules, and a quantum description is required in order to explain and predict the outcome of experiments. In this context, the Feynman path integral formulation of quantum mechanics is a very powerful tool that is amenable to large-scale simulations. We will show how path integral simulations can be used to predict the properties of molecular rotors trapped in superfluid helium and hydrogen clusters. We will show that microscopic Andronikashvili experiments can be viewed as a measurement of superfluidity in a quantum mechanical frame of reference. We will also show that path integral ground state simulations can be used to predict the Raman spectra of parahydrogen clusters and solids. We will present ongoing work on the simulation of molecular rotors confined in endohedral fullerene materials such as H2O@C60. The questions we will address include symmetry breaking, spin conversion, the nature of dipole correlations and dielectric response, and entanglement measures. |
Jan. 24, 2018 |
“AWE-somes: All Water-Emulsion Bodies formed by Polelectrolytes at Interfaces”, Kathleen J. Stebe, University of Pennsylvania, Host: Xiao-Min Lin Interfaces between fluids are rich environments to trap materials and build films. Particles and molecules adsorb at interfaces to lower the interfacial energy, and so can be collected from bulk fluid phases to form interfaces covered with monolayer or multilayer structures. This system is an excellent platform for capsule formation. By placing droplets in an external phase, materials from either the dispersed or continuous phases can be incorporated into films. Judicious selection of these components can lead to highly versatile, tailored structures. We are developing encapsulation methods via interfacial complexation of polyelectrolytes and other charged species in all aqueous two phase systems to make multi-functional all water emulsion bodiesAWE-somes. Such capsules might be particularly interesting for sequestration of delicate components, including proteins and microbes, which should not be placed in contact with oils or hydrophobic media. Here we discuss the example of the PEG-Dextran-water system, which separates into PEG-rich and dextran-rich phases. The interfacial tension between the phases is quite low. Furthermore, many molecules, including polyelectrolytes, partition freely between the two phases. These factors make interfacial structure formation especially challenging. We develop strategies to build membranes from complementary polyelectrolytes in each phase by balancing their rates of transport to the interface. To impart additional functionality, we develop methods to include charged nanoparticles (NPs) in such membranes. Here, nanoparticles can be selected that preferentially partition into one of the phases, facilitating interfacial transport, and creating an osmotic imbalance that leads to spontaneous formation of encapsulated multiple emulsions. These AWE-somes, with internal structures reminiscent of membraneless organelles in cells, provide a rich platform for separation, partitioning, reaction, and transport, suggesting AWE-somes might be developed into capsules that mimic biological-cell functions, or protocell systems. |
Jan. 10, 2018 |
“Electronic Excitations in the Condensed Phase”, Tim Berkelbach, University of Chicago. Host: Pierre Darancet I will present recent work developing predictive theories and ab initio computational techniques for the description of excited states in nanoscale and condensed-phase materials. First, I will describe a low-energy theory of band gaps and excitons in atomically-thin semiconductors, focusing on the transition-metal dichalcogenides. In particular, the theory is naturally adapted to include environmental effects, which are critically important for such atomically-thin materials. The presented approach can be viewed as a poor-man’s GW+BSE, which is a successful suite of techniques for excitations in solids, but one which breaks down for more strongly correlated materials. To address this, I will describe the software development and applications of wavefunction-based quantum chemistry techniques for solid-state problems. In particularly the use of coupled-cluster theory for solids is demonstrated to provide an accurate description of satellite structure in the photoemission of metals, correlation-driven bandwidth narrowing, and high-accuracy band gaps in semiconductors. The formal relation to the GW approximation will be briefly discussed. |