Degree

Doctor of Philosophy (PhD)

Department

Chemistry

Document Type

Dissertation

Abstract

This dissertation presents the results for two simulation studies of time-resolved attosecond spectroscopy using first principles with real-time time-dependent density func- tional theory (RT-TDDFT). These simulations are motivated by the new development of attosecond pulses at X-ray free electron laser facilities. The first project details the use of high energy pulses (extreme-UV/X-rays) to probe the strong-field near-infrared (NIR) induced attosecond transient metallization of dielectrics. Bulk mimicking finite clusters are used with transient absorption spectroscopy (TAS) to simulate the core-level spec- troscopy of the dielectrics silica and diamond. Our calculated Si L-edge TAS for silica compares well to the experimental study. We then analyze the C K-edge of diamond, a dielectric whose attosecond response has yet to be studied, with X-rays. Our results cap- ture the periodicity of optical density reduction in silica, and a similar response in the diamond K-edge. The second study involves probing electronic motion in the molecule 4-chlorocinnamaldehyde using X-rays in a ω/2ω pump/probe scheme. These dynamics are initiated via ionization of the Cl 2p electron (∼ 260 eV) which then causes electronic motion in the valence shell. This movement can then be observed via probing changes in the O K-edge features (∼ 520 eV). Our simulations determine through analysis of electron density and oscillations in the brightest feature of the TAS that electronic motion occurs across the molecule at a period of roughly 1 fs.

Date

6-26-2025

Committee Chair

Kenneth, Lopata

DOI

10.31390/gradschool_dissertations.6825

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Available for download on Thursday, June 24, 2032

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