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Center for Nanoscale Materials

CNM Colloquium Series

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


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


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


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, ABSTRACTHYBRID 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 peptidesBradley Pentelute, Massachusetts Institute of Technology, Host: Chris Fry, ABSTRACT

May 25, 2022

10:00 am 

Photon Correlation as a Resource in Microscopy and SpectroscopyDan Oron, Weizmann Institute of Science, Host Xuedan Ma. ABSTRACT
Apr 27, 2022 Materials Chemstry for Optoelectronics and for DecarbonizationTed 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


Mar 30, 2022

Mobile Optical Excitations in Two-Divensional MaterialsAlexey Chernikov, University of Regensburg (Germany), Host: Darien Morrow.  ABSTRACT
Mar 2, 2022 Macroscope Materials from Nanoparticle AssemblyRobert Macfarlane, MIT (Department of Materials Science and Engineering), Host: Elena Shevchenko, ABSTRACT
Feb 16, 2022 Synthesis and Applications of Colloidal Nanorod HeterostucturesMoonsub 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, biocompositesBethanie 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 scaleJeffrey 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 InterfaceElena 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 PhotonicsIgor 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 RobotsJoshua Schrier, Fordham University, Host: Pierre Darancet.  Abstract
June 9, 2021 Single and Multicomponent Superlattice Structures with Perovskite Nanocrystals; Structural Diversity and Collective EmissionMaksym 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 SymmetriesAndrea Alu, City University of New York (CUNY), Host: Pierre Darancet, ABSTRACT
April 14, 2021 Robot-accelerated Materials Discovery: From Perovskites to Photon AvalanchesEmory Chan, Lawrence Berkeley National Laboratory, Host: Jie Xu. ABSTRACT
Mar. 31, 2021 On-surface Reactions and Single Molecule Charge Transitions Controlled by Atomic ManipulationLeo 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 NanoscaleBo 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 POSTPONEDJosh Goldberger, Ohio State University, Host: Xuedan Ma
May 18, 2020 CANCELED - Data-driven Discovery of Two-dimensional Quantum Materials: The Role of Symmetry and Motif, Qimin Yan, Temple University, Host:  Pierre Darancet   ABSTRACT
Feb. 19, 2020 Biologically Germane Sensing with Aptamer-Field-Effect TransistorsAnne 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 HeterostructuresBrian 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


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 ModesLiang Jiang, University of Chicago - PME, Host: Xufeng Zhang  ABSTRACT
Oct 30, 2019 Electronics for the Next 50 YearsQing 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 NanoparticlesEugenia 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 PromiseM. Ishaque Khan, Illinois Institute of Technology, Host: Ralu Divan  ABSTRACT
Aug. 7, 2019 Quantum Optomechanics and Engineered DissipationAashish Clerk, Institute for Molecular Engineering, University of Chicago.  Host:  Matthew Otten . ABSTRACT
July 24, 2019 Nanotechnology: From Graphene to Molecular NanomachinesJames 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 SimulatorsAndrew Ferguson, University of Chicago, Host: Subramanian Sankaranarayanan  ABSTRACT
May 29, 2019 Maxwellian Phases of MatterZubin Jacob, Purdue University, Host: Peijun Guo, ABSTRACT
May 15, 2019 Computational Modeling and Screening of Semiconductor Electrodes for Solar-to Fuel ConversionIsmaila Dabo, Penn State, Host: Pierre Darancet, ABSTRACT
May 1, 2019 Manifestation of Spin-Couplings in Computational Molecular SpectroscopiesXiaosong 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 SpectroscopyBern Kohler, Ohio State University, Host: Gary Wiederrecht, ABSTRACT
Apr. 11, 2019
Special Colloquium
CANCELED - Stimulated Emission by Colloidal Quantum DotsZeger Hens, Ghent University, Host:  Richard Schaller, ABSTRACT  - CANCELED
Mar. 20, 2019 Crafting Light at the Nanoscale with 2D Materials and MetasurfacesAlexander High, University of Chicago, Host:  Jeff Guest, ABSTRACT
Feb. 20, 2019 Fundamental Properties and Device Prospective of Emerging two-Dimensional MaterialsHan Wang, University of Southern California, Host: Xu Zhang, ABSTRACT
Feb. 6, 2019 CANCELED - Electron Photoemission from Diamond and Integration of Plasmonic Nanoparticles into DiamondRobert 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 DimensionsP. 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 BeyondHaiyan 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 DotsDong 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 FunctionalitiesQuanxi 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 AssemblyNicholas A. Kotov, University of Michigan.  Host:  Gleiciani de Queiros Silveira
Inorganic nanoparticles (NPs) have the ability to self-organize into variety of structures with sophisticated and dynamic geometries. Analysis of experimental data for different types of NPs indicates a general trend of self-assembly under a wider range of conditions and having broader structural variability than self-assembling units from organic matter. Remarkably, the internal organization of self-assembled NP systems rival in complexity to those found in biology which reflects the biomimetic behavior of nanoscale inorganic matter. In this talk, the following questions will be addressed:
(a) What are the differences and similarities of NP self-organization compared with similar phenomena involving organic and biological building blocks?
(b) What are the forces and related theoretical assumptions essential for NP interactions?
(c) What is the significance of NP self-assembly for understanding emergence of life?
(d) What are the technological opportunities of NP self-organization?
Self-organization of chiral nanostructures will illustrate the importance of subtle anisotropic effects stemming from collective behavior of NPs and non-additivity of their interactions. The fundamental significance of studies in this area from this and other groups will be discussed in relation to the origin of homochirality on Earth and spontaneous compartmentalization (protocells). The practicality of self-organization of nanoparticles will be discussed in relation to charge storage technologies, DNA/protein biosensing, chiral catalysis, and combating antibiotic resistant bacteria and other infections including rapidly mutating viruses.
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2. Kotov, N. A. Inorganic Nanoparticles as Protein Mimics, Science, 2010, 330(6001), 188–189.
3. Srivastava S.; et al., Light-Controlled Self-Assembly of Semiconductor Nanoparticles into Twisted Ribbons, Science, 2010, 327, 1355.
4. Yeom, J.; et al., Chiral Templating of Self-Assembling Nanostructures by Circularly Polarized Light, Nature Mater. 2015, 14, 66.
5. Batista-Silvera, C.; Larson, R.; Kotov, N. A. Non-Additivity of Nanoparticle Interactions, Science, 2015, DOI: 10.1126/science.1242477.
6. L.Liu, et al. Low-Current Field-Assisted Assembly of Copper Nanoparticles for Current Collectors, Faraday Disc. 2015, 181, 383-401.
7. M. Yang, H. Chan, G. Zhao, J.H. Bahng, P. Zhang, P. Král, N.A. Kotov, Self-Assembly of Nanoparticles into Biomimetic Capsid-Like Nanoshells, Nature Chemistry, 2016, 9, 287–294.
8. J. H. Bahng, B. Yeom, Y. Wang, S. O. Tung, N.A. Kotov, Anomalous Dispersions of Hedgehog Particles, Nature, 2015, 517, 596–599.
9. W. Feng, J.-Y. Kim, et al. Assembly of Mesoscale Helices with Near Unity Enantiomeric Excess and Light-Matter Interactions for Chiral Semiconductors, Science Advances, 2017, 3(3), e1601159.
10. S. Jiang, et al. Chiral Ceramic Nanoparticles of Tungsten Oxide and Peptide Catalysis, Journal of the American Chemical Society, 2017, 139 (39), 13701–13712

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.