Events in physical chemistry.

Formation and dissociation of hydrocarbons under interstellar conditions

Abstract: Hydrocarbons of all shapes and sizes are found throughout the various stages of star- and planet formation. Recently, using radio astronomical observations, a variety of cyclic- and even polycyclic hydrocarbons have been detected in the very cold (10 K) Taurus molecular cloud. These detections challenge our understanding of the chemical formation mechanisms under these low-temperature and low-density conditions.

Theoretical Approaches to Photoinduced Charge Transfer in the Condensed Phase

Abstract: Photoinduced charge and energy transfer in condensed-phase systems plays a crucial role in solar energy conversion, particularly in organic photovoltaic (OPV) materials. This talk will introduce newly developed computational frameworks that integrate three levels of description: rate constants, time-dependent rates, and nonadiabatic dynamics. At the core of these approaches is the linearized semiclassical (LSC) method, which enables the study of electronic transitions in complex many-body systems at an all-atom resolution.

Accelerating the Computational Design of Functional Organic Molecules and Polymers

Abstract: Functional materials design often requires that the desired molecules (or materials) simultaneously satisfy multiple desired properties, such as electrochemical properties, stability, and synthetic accessibility. This talk will discuss several strategies we have developed for efficiently navigating chemical space and accelerating the inverse design of new functional organic molecules and materials, and the physical insights we gain during their design and deployment.

On-Demand Control of Single-Molecule Chemistry through Vibrational Characterization and Manipulation

Abstract: Chemical processes hinge on the dynamic rearrangement of nuclei within molecules. Controlling these motions with precision has been a long-standing goal in chemistry. My lab focuses on achieving this by manipulating interactions between individual molecules and their nanoscale environment. We engineer the potential energy surface at this scale to control molecular properties such as structure and reactivity.

Investigating Various Fascinating Aspects of Gold Nanoparticles in DNA Research, Material Science, and Cancer Therapy

Abstract: In this talk, we will explore the intriguing interactions between DNA and gold nanoparticles, focusing on their newly explored binding mechanisms. Key topics will include the selective binding of gold nanoparticles to mismatched and/or single-stranded regions of double-stranded DNA and the subsequent movement of these particles along the DNA molecule over the long molecular distances.

Urban Air Quality in the Anthropocene

Abstract: Urban air quality in the U.S. has generally been improving for many decades. Decreasing emissions of nitrogen oxides (NOx) and anthropogenic volatile organic compounds (VOCs) have caused decreases in ozone concentrations, albeit in a highly non-linear fashion. In this seminar, I will present results from a summer 2022 study in the LA basin. We observed lower VOC emissions than during previous studies. However, concentrations of secondary pollutants had not decreased, indicative of changes in the NOx-VOC regime.

How does interfacial tension affect droplet nucleation and melting point depression in nanoparticles?

Interfacial tension controls many important nanoparticle physicochemical properties. As the particle diameter decreases the vapor pressure over a curved particle increases and the melting point decreases. This, in turn, influences phase transitions (nucleation of new particles, deliquescence and efflorescence, ice nucleation, and cloud droplet nucleation), the degree to which particles take up water at elevated relative humidity, and the tendency of particles to evaporate. Current theories are based on Gibbs’ thermodynamics, which yield the Kelvin equation and Gibbs-Thomson equation.

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