Physics Colloquium

Physics Colloquium

Friday, April 26, 2019

Time: 12 pm - 1:30 pm

Location:EACSB 1.104 (Edinburg), BLHSB 1.104 (Brownsville)

Harnessing the intermolecular Coulombic decay mechanism for targeted energy transfer in solution

Intermolecular Coulombic decay (ICD) is a well-established mechanism for energy transfer between core-excited atoms and their neighbors. Some years ago, my collaborators and I used plane-wave density functional theory (pwDFT) and a simple density-of-states (DOS) comparison to explain ICD-related features in the x-ray photoelectron spectrum of aqueous NaOH. Here I present extensions of this qualitative approach for predicting ICD that depend only on information easily obtained by molecular dynamics simulation and pwDFT. Specifically, we develop energetic criteria based on excess overlap between chemically distinct contributions to the total DOS, as well as complementary spatial criteria based on the radial distribution function. We use these measures to predict the preferred target for ICD from core-excited bismuth(III) in an aqueous solution containing citrate anions and 1,4-dioxane. Synchrotron experiments demonstrate not only that citrate is the target, as predicted, but that there is a fivefold enhancement in the citrate:dioxane destruction ratio over background radiolysis (i.e., in the absence of bismuth) that drops off as bismuth precipitates from the solution. I will discuss how our criteria can be used to screen for ICD propensity and how to estimate near-field effects in the corresponding measurements using analytic calculations of solid angles. Throughout, I will emphasize that these insights may contribute to the development of new coadjuvant therapies for use in cancer radiotherapy. Time allowing, I will summarize other current research and opportunities in my group for students in the Department of Physics and Astronomy.

Speaker: Dr. Shervin Fatehi (UTRGV, Chemistry)

Dr Fatehi

About the speaker: Shervin Fatehi earned an S.B. in chemistry from MIT in 2004. He spent a year studying the statistical mechanics of liquids with David Chandler at UC Berkeley before changing focus to approximate quantum dynamics methods and theoretical X-ray spectroscopy, completing a Ph.D under the supervision of William H. Miller and Richard J. Saykally in 2010. During consecutive postdoctoral appointments (2011–2015) with Joseph E. Subotnik (University of Pennsylvania) and Ryan P. Steele (University of Utah), he developed expertise in nonadia- batic phenomena, analytic gradient theory, and ab initio molecular dynamics. In Fall 2015, Dr. Fatehi joined the founding faculty of UTRGV as a member of the Department of Chemistry. His current research focuses on the development of theoretical and computational methods that deepen our understanding of the interplay between the electronic structure of molecules (quantum chemistry), their motions and rearrangements (chemical dynamics), and their inter- actions with light (spectroscopy). Projects include exploring the importance of nonadiabatic effects in mechanochemistry and the application of stochastic electronic structure methods to simulating molecular motion; the latter work is funded by the Welch Foundation.

Past Physics Colloquium 2019

Past Physics Colloquium 2018

Past Physics Colloquium 2017

Past Physics Colloquium 2003 - 2017

Physics Colloquium