Time-resolved near-edge X-ray absorption fine structure of pyrazine from electronic structure and nuclear wave packet dynamics simulations

Shota Tsuru*, Marta L. Vidal, Mátyás Imre Pápai, Anna I. Krylov, Klaus Braagaard Møller, Sonia Coriani

*Corresponding author for this work

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Abstract

As a demonstration of the analysis of the electronic structure and the nuclear dynamics from time-resolved near-edge X-ray absorption fine structure (TR-NEXAFS), we present the TR-NEXAFS spectra of pyrazine following the excitation to the 1B2u(ππ*) state. The spectra are calculated combining the frozen-core/core-valence separated equation-of-motion coupled cluster singles and doubles approach for the spectral signatures and the multiconfiguration time-dependent Hartree method for the wave packet propagation. The population decay from the 1B2u(ππ*) state to the 1B3u(nπ*) and 1Au(nπ*) states, followed by oscillatory flow of population between the 1B3u(nπ*) and 1Au(nπ*) states, is interpreted by means of visualization of the potential energy curves and the reduced nuclear densities. By examining the electronic structure of the three valence-excited states and the final core-excited states, we observe that the population dynamics is explicitly reflected in the TR-NEXAFS spectra, especially when the heteroatoms are selected as the X-ray absorption sites. This work illustrates the feasibility of extracting fine details of molecular photophysical processes from TR-NEXAFS spectra by using currently available theoretical methods.
Original languageEnglish
Article number124114
JournalJournal of Chemical Physics
Volume151
Issue number12
Number of pages22
ISSN0021-9606
DOIs
Publication statusPublished - 2019

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