VCU Department of Physics Colloquia: Spring 2019
The journey to a new science frontier at Jefferson Lab, from 12 GeV to the Electron-Ion Collider
Friday, March 22 at 4:00 pm in 701 W. Grace St., Room 2310
The understanding of the structure of matter at the level of atoms and molecules is a cornerstone of the technical achievements of the modern civilization; everything from modern medicine to communication infrastructure depend on this knowledge. The current understanding of the internal structure of nucleons – protons and neutrons - and nuclei, however, are at a comparatively primitive level. While we know the interior landscape of nucleons includes a strong-force driven sea of quarks, antiquarks and gluons, with a net surplus of a few ever-present valence quarks, we have very little idea how the macro-properties and structure of nucleons and nuclear matter emerge from their strong dynamics. This lack of understanding has been due both to the difficulty of the theory of Quantum Chromodynamics (QCD) that govern quarks and gluons, and experimental limitations. Advances in the theoretical understanding of QCD in the past decades, however, have led to a framework that enables to precisely image the gluons and quarks, and to understand the role they and their interactions play in nucleons and nuclei. The Jefferson Lab 12-GeV accelerator uses electrons to initiate this “nuclear femtography” program to image the quark and gluon structure of nucleons and nuclei. Ultimately, a new accelerator facility is required to understand the role of the gluons that bind us all, the Electron-Ion Collider. This would be the world's first polarized electron-proton collider, and the world's first e-A collider.
Rational Design of Materials for a Clean Energy Future
Prof. Puru Jena
Department of Physics, Virginia Commonwealth University
Friday, February 22 at 4:00 pm in 701 W. Grace St., Room 2310
Clean, abundant, and sustainable energy is undoubtedly one of the greatest challenges in the 21st century. Fossil fuels that account for more than 80% of the world’s current energy needs are not only limited, but also are harmful to the environment. While renewable energy sources such as solar and hydrogen together can meet this need, considerable material challenges remain before they can reduce our dependence on fossil fuels. In addition, efficient batteries have to be developed to store this energy. This talk will deal with some of the material challenges in energy harvesting and storage, with particular emphasis on Li- and Na-ion batteries, and perovskite-based solar cells. A common feature of all these materials is that they are complex salts where their negative ion components can be identified as super-halogen clusters mimicking the chemistry of halogens, but with electron affinities that far exceed that of any halogen atom. This realization has made it possible to use the vast advances in cluster science to design novel materials for energy applications. I will discuss how a rational design of clusters can lead to the synthesis of halogen-free electrolytes in metal-ion batteries, anti-perovskites for superionic conductors, and organic hybrid perovskites for solar cells. Experimental evidence will be provided to establish the predictive capability of our theory.
Topological Quantum Materials for Battery Anode Applications
Prof. Qiang Sun
Peking University, Beijing, China
Friday, February 15 at 4:00 pm in 701 W. Grace St., Room 2310
Battery science and technology are of current interest. While the specific capacity of the commercially used graphite anode for lithium battery is limited to 372 mAh/g. Extensive efforts have been devoted to improve the performance but not much progress was made during the past 25 years. Inspired by the 2016 Nobel Prize in Physics for topological state and phases of materials, we have explored the possibility of using topological semimetal materials (TSMs) for metal-ion battery anode having the merits of intrinsic high electronic conductivity and ordered porosity for metal ions transport. In this talk, we will focus on all carbon based porous topological semimetal for Li-ion battery anode, all silicon based porous topological semimetal for Na-ion battery anode, and high-pressure-assisted design of porous topological semimetal carbon, which range from synthesis simulation to property predictions, bridging quantum materials physics and battery technology. We will show that topological quantum materials are promising for ion battery anode applications with the merits of high capacity, fast kinetics and good stability going beyond the conventional anode materials.
“Building from Nature” - Bioinspired materials for the fabrication of functional devices
Dr. Vamsi Yadavalli
Department of Chemical and Life Science Engineering, Virginia Commonwealth University
Friday, February 8 at 4:00 pm in 701 W. Grace St., Room 2310
Biomimetic composites of naturally derived and synthetic polymers provide exciting opportunities to develop soft, flexible, biocompatible, and physiologically compliant devices for diverse applications in healthcare. Bioinspired materials can serve not only as the structural, but also as the functional components of such devices. This poses material-specific functionalization and fabrication related challenges in the design and fabrication of these systems. Natural silk protein biopolymers show tremendous promise in this regard due to intrinsic properties of mechanical performance, optical transparency, biocompatibility, biodegradability, processability, and the ability to stabilize biomolecules. The exceptional ensemble of properties provides opportunities to employ silk proteins for numerous applications.
This talk will discuss some of the recent work from our group in transitioning from the silk cocoon to protein based biocomposites that can be used as biosensors, electrodes, biophotonic elements, drug delivery vehicles, and energy storage devices. By integrating microfabrication tools with natural materials, we show how high resolution, high fidelity structures can be patterned in both rigid and flexible formats in two and three dimensions. Composites with materials such as conducting polymers provide added functionality as opto-electronic architectures. The ease of fabrication, biochemical functionalization, biocompatibility, as well as tunable mechanical properties and biodegradation of these biomaterials provide unique possibilities as sustainable, bioresorbable protein microdevices.
Adventures in Carbon Cluster Chemistry Using Helium Droplet Methods
Dr. William K. Lewis
Senior Research Chemist, Fuel and Energy Branch, Air Force Research Laboratory
Friday, February 1 at 4:00 pm in 701 W. Grace St., Room 2310
Carbon is a fascinating element with a rich chemistry to explore. In the bulk, it adopts the familiar graphite and diamond allotropes; on the nanoscale, it produces fullerenes, graphenes, and nanotubes; and with only a few atoms, it forms clusters with linear, cyclic, and cage structures. The many forms of carbon find application in a wide variety of fields, from materials science to combustion to astrochemistry. We are using helium droplet methods to assemble small neutral carbon clusters from-the-ground-up, and to examine their structure, energetics, and interaction with other molecules of interest. In this talk we will discuss assembly processes to produce carbon clusters in a systematic way, measurements of binding energies and structures, and results from rovibrational spectroscopy of the C3-H2O complex.
Metallic Clusters Supported on Graphene as Efficient Materials for Hydrogen Storage
J. Ulises Reveles
Department of Physics, Virginia Commonwealth University
Friday, January 25 at 4:00 pm in 701 W. Grace St., Room 2310
Recent studies suggest that graphene decorated with transition and light metal atoms is a feasible alternative for the design of the next generation of hydrogen storage systems, that is, materials which require a gravimetric content of at least 7.5 wt%, and an adsorption energy of 0.2–0.6 eV per H2.
We present a first principles study of hydrogen adsorption in palladium (Pdx), titanium (Tix), nickel (Nix), and bimetallic TixAly clusters supported on graphene. Our results show that selected clusters present an enhanced hydrogen gravimetric content up to 3.2–3.6 wt%, and support the hypothesis controlled introduction of small metal clusters to graphene is a feasible way to enhance its hydrogen gravimetric content. Furthermore, our study opens up the possibility of investigating other binary TMx–Ay (TM = transition metal and A = main group) clusters supported on graphene as promising candidates for hydrogen storage.
Strong-Field Chemistry of Ions and Radicals: Ultrafast Dynamics and Nanomaterial Synthesis
Department of Chemistry, Virginia Commonwealth University
Friday, January 18 at 4:00 pm in 701 W. Grace St., Room 2310
Ionizing radiation can be destructive when it causes damage to DNA, but also can be constructive when used to synthesize novel nanomaterials without toxic chemicals. High-intensity, ultrashort (picosecond-femtosecond) laser pulses can mimic many properties of ionizing radiation such as X-rays, using visible or infrared wavelengths instead. This talk will highlight recent recent results in our laboratory using strong-field femtosecond laser pulses to induce ion chemistry. First, we will present ultrafast dynamics measurements of organophosphorus and nitrotoluene radical cations using pump-probe techniques. The organophosphorus molecules dimethyl methylphosphonate (DMMP) and trimethyl phosphate (TMP) model the DNA sugar-phosphate backbone, so their radical cation dynamics can provide insight into reaction pathways occurring in DNA upon removal of an electron from the phosphate group. The nitrotoluenes model explosives such as TNT, making their dissociation dynamics relevant to energetic material development. The ionization-induced coherent vibrational dynamics in both families of molecules will be discussed. The second part of the talk will discuss applications to nanomaterials synthesis of high-density plasmas consisting of free electrons and OH• radicals formed by focusing femtosecond laser pulses in aqueous solution. The plasma electrons can reduce metal ions in solution to form metal nanoparticles, and the hydroxyl radicals can result in accelerated particle growth or back-oxidation, depending on the target metal. We will discuss the mechanisms leading to the conversion of tetrachloroaurate ([AuCl4]-), silver nitrate (AgNO3), and copper acetate (Cu(OAc)2) to Au, Ag and Cu nanoparticles both in aqueous solution and in the presence of a silicon wafer. When silicon is present, the metal nanoparticles can be isolated in a silica matrix, which prevents their aggregation and yields ultrasmall ~2 nm particles.
VCU Department of Physics Colloquia: Fall 2018
Applications of Lithium-Ion Batteries in Electric Drive Vehicles
Tien Quang Duong
Vehicle Technologies Office, U.S. Department of Energy
Friday, November 30 at 4:00 pm in 701 W. Grace St., Room 2310
Supathorn (Supy) Phongikaroon, PH.D., P.E.
Department of Mechanical and Nuclear Engineering, VCU
Friday, November 16 at 4:00 pm in 701 W. Grace St., Room 2310
A rapid overview of high-speed atomic force microscopy: it's impact and applications.
Dr. Loren Picco
Department of Physics, VCU
Friday, November 9 at 4:00 pm in 701 W. Grace St., Room 2310
I will provide an introduction to my research into scanning probe microscope development and instrumentation. I will go over some of the high-impact areas of research that it has been used for and then round off with some highlights of my most recent work and plans now that I am establishing my lab at VCU.
A look into the fabrication,characterization and applications of 2D hemetene.
PhD candidate in Nanoscience
VCU Department of Physics
Friday, November 2 at 4:00 pm in 701 W. Grace St., Room 2310
Personalizing cancer therapy with nanoscience tools
Graeme F. Murray
MD/PhD candidate in Nanoscience
VCU School of Medicine and Department of Physics
Friday, October 26 at 4:00 pm in 701 W. Grace St., Room 2310
Dr. Magdalena K. Morgan
VCU Innovation Gateway
Friday, October 5 at 4:00 pm in 701 W. Grace St., Room 2310
Dr. Morgan will explain how the Innovation Gateway is helping students, faculty and researchers commercialize their inventions and creative work. She works with a team of technical professionals, business developers and administrators to guide and support VCU faculty, staff and trainees in the process of technology transfer to industry. Her talk will discuss how the Innovation Gateway conducts intellectual property evaluation and protection, technology marketing, start-up creation, and new programs to promote a culture of innovation here at VCU.
Modified Dark Matter: Relating Dark Energy, Dark Matter, and Baryonic Matter
Dr. Doug Edmonds
Department of Physics, Penn State-Hazelton
Friday, September 28 at 4:00 pm in 701 W. Grace St., Room 2310
Modified dark matter (MDM) is a phenomenological model of dark matter, inspired by gravitational thermodynamics. For an accelerating Universe with positive cosmological constant ($\Lambda$), such phenomenological considerations lead to the emergence of a critical acceleration parameter related to $\Lambda$. Such a critical acceleration is an effective phenomenological manifestation of MDM, and is found in tight correlations between dark matter and baryonic matter in galaxy rotation curves, the so-called Mass Discrepancy Acceleration Relation (MDAR). The resulting MDM mass profiles are consistent with observational data at both the galactic and cluster scales.
Synthetic Strategies of some Nanostructured Materials
Dr. Tarek M. Abdel-Fattah
Department of Chemistry and Applied Research Center at Thomas Jefferson National Accelerator Facility and Department of Molecular Biology and Chemistry at Christopher Newport University
Friday, September 21 at 4:00 pm in 701 W. Grace St., Room 2310
Nanotechnology deals with materials with dimensions in the range of 1 nm to 100 nm. Materials in that range (1-100 nm) possess novel properties and characteristics different from bulk materials. Therefore, nanotechnology has been of increasing interest in the last decade and used as catalysts, sensors, solar cells and in water decontamination systems. We will present the detailed insights into two synthetic strategies, bottom-up and top-down, for nanomaterials fabrication. In addition, we will report the synthesis and assembly of highly ordered multiple tube-in-tube nanostructures within porous materials.