Tags: Physical Seminar


Comparison of Multifidelity Machine Learning Models for Potential Energy Surfaces

Multifidelity modeling is a technique for fusing the information from two or more datasets into one model. It is particularly advantageous when one dataset contains few accurate results and the other contains many less accurate results. Within the context of modeling potential energy surfaces, the low fidelity dataset can be made up of a large number of inexpensive energy computations that provide adequate coverage of the N-dimensional space…


Vibrational Spectral Signatures and Ultrafast Dynamics of Strong H-bonds Investigated with Cryogenic Ion and 2D IR Spectroscopies

H-bonding interactions and proton transfer processes play central roles throughout chemistry and biology. Spectroscopic studies that directly probe strong H-bonds and proton transfer reactions, however, remain a formidable experimental challenge. We aim to characterize vibrational spectral signatures and dynamics of strong H-bonds by complementing high-resolution gas-phase techniques (cryogenic ion spectroscopy) with ultrafast time-resolved…


Gas-Phase Copper Clusters: Model for the CO2 Reduction Catalyst?


Seeking the Tricorder: Evolution of the NASA Anomaly Gas Analyzer

Dr. Jeffrey S. Pilgrim, winner of the 2023 UGA Chemistry Distinguished Alumnus Award, is President and founder of Vista Photonics, an optical instrumentation company located in Las Cruces, NM. He formed the corporation in June 2003 to develop and commercialize optical gas sensing technologies and instrumentation. Before starting Vista Photonics, Dr. Pilgrim worked as a Senior Research Scientist in a similar research and development environment…


Alginate Gels Structure-Thermodynamic Relationship with Water and Counterions

Microbial communities are predominantly found in biofilms, which are composed of extracellular polymeric substances (EPS). The EPS matrix is engineered and reconfigured by microbes, making it difficult to distinguish between the biotic and abiotic origins of biofilm properties. To establish this distinction, simplify models of the EPS matrix, the study uses molecular dynamic(MD) simulation to predict the nanoscale structure of a model…


Field-Free Molecular Alignment and Orientation

Control of molecular orientation and alignment has been a longstanding goal in chemical reaction dynamics because the outcome of chemical reactions inherently depends on the relative orientation of the colliding species. The earliest methods for obtaining molecular alignment and orientation relied on static electric fields strong enough to overcome the molecule's rotational energy, but these types of techniques are limited by the relatively low…


Optical Properties of Biomass Burning Aerosols from the G-WISE Campaign

Wildland fires contribute significantly to the total carbonaceous aerosol mass concentration in the troposphere. These aerosols, formed from the combustion of biomass fuels, exhibit strong absorption and scattering of visible light, which impacts the radiative forcing in the troposphere. The Georgia Wildland-fire Simulation Experiment (G-WISE), conducted in Athens, GA during October-November 2022, was designed to develop a scientific basis for…


Controversy on Venus: The Existence of Phosphine

In 2020, Greaves et al. concluded from two independent data sources that phosphine is present in the cloud decks of Venus. Their study focused on the fundamental first rotational transition (J = 1-0) of PH3 and their detection of phosphine is solely based on this single transition. Given the importance of phosphine as a possible biosignature and our current understanding of the chemistry of Venus, multiple studies…


Applications of Material Science in Support of Nuclear Forensics and Non-Proliferation

With globalization and the spreading availability of technologies, nuclear proliferation challenges continue to grow and evolve. Savannah River National Laboratory (SRNL) works to counter proliferation by providing scientific and technological solutions, as well as expert advice to combat emerging threats. Working with the National Nuclear Security Administration (NNSA) and other government agencies, SRNL’s Global Security Directorate provides…


Strategies for the Reduction of Detailed Chemical Kinetics Mechanisms

Detailed chemical kinetics mechanisms describing low-temperature combustion often include thousands of species and reactions due to the abundance of intermediates and their complex potential energy surfaces. While these mechanisms are necessary for accurately predicting species concentrations and global combustion metrics, they are often too large for practical engine simulations that require computational fluid dynamics. As such, strategies…
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