Previous APMS Colloquia
Spring 2024
Thursday, April 4, 3:00-4:00 pm
Dr. Lisa Prato
Stellar Astronomy/Exoplanets
Lowell Observatory
Young Binary Stars and Planet Formation
Abstract: As a solitary star with no stellar companion, our Sun is in the minority: at least 60-70% of stars are located in systems of two or three or more components. For the study of star and exoplanet formation, binary stars represent both an opportunity and a problem. On one hand, simple Keplerian physics yields dynamical stellar mass, the most fundamental property of a star, as well as orbital characteristics. Binary star components’ shared age and environment also provides a useful control on comparisons of physical properties. On the other hand, location in a multiple star system impacts the evolution of planet-forming circumstellar disk material and complicates scientists’ identification of individual stellar properties. Nevertheless, given their ubitquity and usefulness, young binaries merit close attention. In the context of the relevant applied physics, e.g., mechanics, spectroscopy, and statistical mechanics, I will describe my research on the determination of young star masses and the potential for planet formation in the binary star environment. I will highlight the contributions of my team, including a number of NAU students, to these efforts.
Thursday, March 28, 3:00-4:00 pm
Prof. Steve G. Greenbaum
Hunter College of the City University of New York
Can we make safe and affordable batteries for electric cars and large scale grid storage? A personal view through recent liquid state and solid state nuclear magnetic resonance investigations of novel electrolytes
Abstract: All major automobile companies will cease manufacturing internal combustion-powered vehicles within a timeframe measured in years rather than decades. The need for mitigating “range anxiety” affordably and without sacrificing safety presents a major challenge to present-day lithium ion technology, which has nearly reached its physical limit in energy density. New chemistries with correspondingly new materials are needed for the next generation of batteries. The major bottleneck in all of these current and proposed developments is the lack of a suitable electrolyte needed to eliminate the flammable liquid carbonate electrolyte solvents in use today. In the realm of large scale grid storage, redox flow batteries, in which energy is stored in large electrolyte-containing tanks, are leading candidates because they are not “footprint” limited.
Our laboratory is focused on application of various nuclear magnetic resonance (NMR) techniques to help understand structure and dynamics of energy storage materials, in particular novel electrolytes. In this presentation we discuss two recent collaborative efforts.
(i) Deep eutectic solvents (DES), are defined as a mixture of two or more species, typically a hydrogen bond donor (HBD) and a hydrogen bond acceptor (HBA) which may be solid or liquid, and that at a particular composition present a melting point depression usually resulting in being a liquid at room temperature. Among their most relevant properties are low volatility, low flammability and wide electrochemical and thermal stability windows. Unlike typical ionic liquids, DESs can be inexpensive, readily synthesized, and can often be prepared from biodegradable, and nontoxic constituents. This makes them attractive candidates, when suitable electrochemically active reagents are added, for redox flow battery applications.1 For the work described in this presentation, in collaboration with the University of Tennessee and Case Western University, the molecular rotational and translational dynamics of several different DESs based on choline chloride (ChCl) were studied using the fast field-cycling nuclear magnetic resonance relaxometry (FFC-NMR) and pulsed-field gradient (PFG) NMR techniques.1
(ii) The second project (with L. Hu, et.al., University of Maryland) concerns cellulose nanofibers (CNF) derived from natural wood materials. Introducing Cu2+ into the CNF creates molecular channels through which Li+ ions can more readily move. Solid state magic angle spinning (MAS) 1H NMR provides estimates of the residual solvent molecules present in Li-Cu-CNF materials, which aids the Li+ ions transport mechanism without compromising electrochemical stability. PFG NMR was used to measure the diffusivity of Li+ and anion and to estimate the Li+ transference number (tLi+), which turns out to be significantly greater than observed in other polymer-based electrolytes.2
Finally, time permitting, aspects of my own personal views and experiences on student mentoring will be presented.
1. “Dynamics of Glyceline and Interactions of Constituents: A Multi-technique NMR study”, C. Fraenza, et.al. Journal of Physical Chemistry B, 126, 890 (2022) https://doi.org/10.1021/acs.jpcb.1c09227
2. “Copper-coordinated cellulose ion conductors for solid-state batteries”, Chunpeng Yang et al., Nature 598, pages, 590 (2021) https://doi.org/10.1038/s41586-021-03885-6
Thursday, February 22, 3:00-4:00 pm
Dr. Katherine Jungjohann
National Renewable Energy Laboratory
Interfacial Reactions in Materials using Advanced Microscopy
Abstract: An interfacial understanding is needed in many material science challenges, where we have used advanced microscopy techniques for corrosion, Li-metal batteries, and degraded solar modules. The electrode-electrolyte interface is challenging to probe, but new methods and tools are enhancing our understanding of these interfaces. Liquids pose a significant challenge for high-resolution scanning transmission electron microscopy (STEM) due to the high vacuum environment required for optimal imaging conditions. Two strategies will be covered in this seminar, operando liquid-phase STEM and cryogenic STEM, for characterizing nanoscale detail from these solid-liquid interfaces. Our objective understanding of these nanoscale mechanisms can be greatly improved by combining the high-resolution detail with micro-to-millimeter scale compositional and structural mapping with cryogenic focused ion beam scanning electron microscopy. This seminar will cover the use of these advanced microscopy methods for low-carbon steel corrosion that identifies a possible mechanism for pit formation, morphology of electrodeposited lithium metal in aprotic solvents, and encapsulant reactions at a silicon solar cell surface from water and sodium migration. The tools, methods, and results of these studies will be detailed in this presentation.
Thursday, January 25, 3:00-4:00 pm
Dr. Thomas Holschuch II
Idaho National Laboratory
Integration of Physics and Engineering at Idaho National Laboratory
Abstract: Idaho National Laboratory is a Department of Energy site spreading over 890 square miles. With four operating nuclear reactors, it is the primary DOE facility for nuclear research, but has a recent expansion in cybersecurity and critical infrastructure. The integration of physics and engineering provides a better understanding for concepts found in these fields. For nuclear research, the concentration of radioactive isotopes is an important parameter to measure in operating reactors and predictions for potenital reactor designs. For isotopes that possess a complicated decay diagram, angular coincidences between gamma rays emitted in a single atomic decay can be measured with two radiation detectors and will lower the sensitivity of a detection system. The Germanium Rotational Measurements for Angular Correlation (GeRMAC) system has been assembled at INL to provide data for nuclear reactor, radiation detector, and nuclear forensics measurements.