Mixed quantum-classical approach to the calculation and assignment of the time- resolved photoelectron spectra

Piteša, Tomislav (2022) Mixed quantum-classical approach to the calculation and assignment of the time- resolved photoelectron spectra. Doctoral thesis, Sveučilište u Zagreb, Prirodoslovno-matematički fakultet.

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Abstract

Time-resolved photoelectron spectroscopy (TRPES) has proven to be one of the most convenient pump-probe techniques for monitoring the coupled nuclear and electronic dynamics. However, in order to "see" the molecular dynamics in the spectrum, the theoretical simulations and assignment of the spectra are needed. In this work, the classical doorway-window formalism has been applied to the TRPES technique. A pragmatic methodology of evaluation of the expression has been designed and implemented. It consists of multireference treatment of bound electronic states, a mixed quantum-classical simulation of nonadiabatic dynamics and static-exchange DFT treatment of the photoionization continuum. Also, a simple procedure of TRPES assignment in the terms of electronic characters, based on the diabatization of the bound electronic states, has been designed and implemented. The methodology as a whole has been applied on two prototype photoinduced processes: internal conversion in pyrazine and the ring-opening reaction in cyclohexa-1,3-diene. New insights in the mechanisms of the studied processes are presented and discussed. In addition, the mechanisms of nitrogen elimination from diazomethane during excitation to the first and second excited state were studied by simulations of nonadiabatic dynamics.

Item Type:

Thesis (Doctoral thesis)

Uncontrolled Keywords:

photoelectron spectroscopy; pump-probe spectroscopy; nonadiabatic dynamics; diabatization; photochemistry; pyrazine; 1,3-cyclohexadiene

Subjects:

NATURAL SCIENCES > Chemistry > Theoretical Chemistry

Divisions:

Division of Physical Chemistry

Projects: