Argonne National Laboratory

Colloquium Series

The Center for Nanoscale Materials holds a regular biweekly colloquium on alternate Wednesdays at 11:00 a.m. in Bldg. 440, Room A105/106. The goal of the series is to provide a forum for topical multidisciplinary talks in areas of interest to the CNM and also to offer a mechanism for fostering interactions with potential facility users.

Committee Members:

  • Xiao-Min Lin (Chair)
  • Pierre Darancet
  • Ralu Divan
  • Xuedan Ma
  • Elena Rozhkova
  • Jianguo Wen

NOTE:

Location: 446 Auditorium

Sep. 6, 2017

"Optical properties of exciton-plasmon nanomaterials: from collective exciton resonances to nonlinear spectroscopy"Maxim Sukharev, Arizona State University.  Host:  Tal Heilpern
 
Recent advances in nanofabrication and optical characterization open a wide variety of new ways to improve our understanding of light-matter interaction. In particular, hybrid materials comprised of plasmon sustaining nanostructures and molecular aggregates present a unique opportunity to study how quantum systems (molecules) behave at plasmonic interfaces. The strong coupling phenomenon plays a crucial role allowing to efficiently transfer energy between plasmons and molecular excitons on a femtosecond time scale. In this talk I will discuss modeling aspects of various optical phenomena at plasmonic interfaces using Maxwell-Bloch equations in one, two, and three dimensions. I will demonstrate that at high molecular concentrations exciton-plasmon nanomaterials exhibit a new type of optical resonance related to strong interaction of a molecular aggregate driven by local plasmon fields. I will also discuss photon echo spectroscopy applied to exciton-plasmon systems.

Sep. 12, 2017 

"Probing Neural Function with Electronic, Optical and Magnetic Materials", Polina Anikeeva, Massachusetts Institute of Technology (MIT).  Host:  Elena Shevchenko

Mammalian nervous system contains billions of neurons that exchange electrical, chemical and mechanical signals. Our ability to study this complexity is limited by the lack of technologies available for interrogating neural circuits across their diverse signaling modalities without inducing a foreign-body reaction. My talk will describe neural interface strategies pursued in my group aimed at mimicking the materials properties and transduction mechanisms of the nervous system. Specifically, I will discuss (1) Fiber-based probes for multifunctional interfaces with the brain and spinal cord circuits; (2) Magnetic nanotransducers for minimally invasive neural stimulation; and (3) Active scaffolds for neural tissue engineering and interrogation.

Fiber-drawing methods can be applied to create multifunctional polymer-based probes capable of simultaneous electrical, optical, and chemical probing of neural tissues in freely moving subjects. Similar engineering principles enable ultra-flexible miniature fiber-probes with geometries inspired by nerves, which permit simultaneous optical excitation and recording of neural activity in the spinal cord allowing for optical control of lower limb movement. Furthermore, fiber-based fabrication can be extended to design of scaffolds that direct neural growth and activity facilitating repair of damaged nerves.
Molecular mechanisms of action potential firing inspire the development of materials-based strategies for direct manipulation of ion transport across neuronal membranes. For example, hysteretic heat dissipation by magnetic nanomaterials can be used to remotely trigger activity of neurons expressing heat-sensitive ion channels. Since the alternating magnetic fields in the low radiofrequency range interact minimally with the biological tissues, the magnetic nanoparticles injected into the brain can act as transducers of wireless magnetothermal deep brain stimulation. Similarly, local hysteretic heating allows magnetic nanoparticles to disrupt protein aggregates associated with neurodegenerative disorders.

Sep. 20, 2017

Jeffrey Neaton, Lawrence Berkeley National Laboratory.  Host:  Pierre Darancet.

The ability to identify and design new materials for energy applications hinges on the development of intuition connecting their properties to chemical composition, atomic-scale structure, dimensionality, and environment. Here I will describe the development and application of new ab initio computational approaches – based on density functional theory, many-body perturbation theory, and materials databases – for prediction of energy conversion phenomena in complex materials. First, I will describe a new formalism and calculations that sheds new light into singlet fission, a multiexciton generation process by which multiple charge carriers may ultimately result from a single photon. Second, I will discuss a new joint experiment and theory high-throughput workflow for identifying a new class of vanadium oxide-based photoanode materials for solar fuels applications. In both cases, I will highlight new intuition and methods developed in these studies, and provide a perspective on future work.

Oct. 18, 2017

Mark Hybertsen, Brookhaven National Laboratory, Center for Functional Nanomaterials.  Host:  Pierre Darancet

Nov. 1, 2017

Alexander Wei,  Purdue University.  Host: Xiao-Min Lin

Nov. 15, 2017

 
Dec. 13, 2017 Norbert Scherer, University of Chicago, Host: Xiao-Min Lin
Jan. 10, 2018 Tim Berkelbach, University of Chicago.  Host: Pierre Darancet
Jan. 24, 2018 Kathleen J. Stebe, University of Pennsylvania, Host: Xiao-Min Lin
Feb. 7, 2018 Pierre-Nicholas Roy, University of Waterloo, Host: Stephen Gray
Feb. 21, 2018 Alexandra Boltasseva, Purdue University, Host: Gary Wiederrecht
Apr. 18, 2018 Nicholas A. Kotov, University of Michigan.  Host:  Gleiciani de Queiros Silveira
May 2, 2018 David S. Ginger, University of Washington, Host: Pierre Darancet
May 16, 2018 Gong Gu, University of Tennessee, Host: Lifen Wang
May 30, 2018 Yugang Sun, Temple University.  Host:  Gary Wiederrecht
Jun. 13, 2018 Mike Arnold, University of Wisconsin, Host: Nathan Guisinger
Jun. 27, 2018 James Alexander Liddle, National Institute of  Standards and Technology (NIST), Host: Ralu Divan
Jul. 11, 2018  
Jul. 25, 2018