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Main Authors: Mayer, Dennis, Titov, Evgenii, Lever, Fabiano, Mehner, Lisa, Murillo-Sánchez, Marta L., Walz, Constantin, Bozek, John, Saalfrank, Peter, Gühr, Markus
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2505.07361
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author Mayer, Dennis
Titov, Evgenii
Lever, Fabiano
Mehner, Lisa
Murillo-Sánchez, Marta L.
Walz, Constantin
Bozek, John
Saalfrank, Peter
Gühr, Markus
author_facet Mayer, Dennis
Titov, Evgenii
Lever, Fabiano
Mehner, Lisa
Murillo-Sánchez, Marta L.
Walz, Constantin
Bozek, John
Saalfrank, Peter
Gühr, Markus
contents We present a combined experimental and theoretical study of the vibrationally resolved valence photoelectron spectra of the complete series of thiouracils (2-thiouracil, 4-thiouracil and 2,4-dithiouracil) for binding energies between 8 and 17 eV. The theoretical spectra were calculated using equation-of-motion coupled cluster theory for ionization potential (EOM-IP-CCSD) combined with the time-independent double-harmonic adiabatic Hessian approach. For all three thiouracils, the first ionization potential is found between 8.4 and 8.7 eV, which is 1 eV lower than for the canonical nucleobase uracil. Ionization bands up to 12 eV show strong vibrational progressions and are well reproduced by the calculations. These bands are attributed to the ionization of (primarily) sulfur- and oxygen-localized valence molecular orbitals. For higher binding energies, the calculations indicate that nonadiabatic couplings are important for the interpretation of the photoelectron spectra.
format Preprint
id arxiv_https___arxiv_org_abs_2505_07361
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Valence photoelectron spectra of thiouracils in the gas phase
Mayer, Dennis
Titov, Evgenii
Lever, Fabiano
Mehner, Lisa
Murillo-Sánchez, Marta L.
Walz, Constantin
Bozek, John
Saalfrank, Peter
Gühr, Markus
Chemical Physics
We present a combined experimental and theoretical study of the vibrationally resolved valence photoelectron spectra of the complete series of thiouracils (2-thiouracil, 4-thiouracil and 2,4-dithiouracil) for binding energies between 8 and 17 eV. The theoretical spectra were calculated using equation-of-motion coupled cluster theory for ionization potential (EOM-IP-CCSD) combined with the time-independent double-harmonic adiabatic Hessian approach. For all three thiouracils, the first ionization potential is found between 8.4 and 8.7 eV, which is 1 eV lower than for the canonical nucleobase uracil. Ionization bands up to 12 eV show strong vibrational progressions and are well reproduced by the calculations. These bands are attributed to the ionization of (primarily) sulfur- and oxygen-localized valence molecular orbitals. For higher binding energies, the calculations indicate that nonadiabatic couplings are important for the interpretation of the photoelectron spectra.
title Valence photoelectron spectra of thiouracils in the gas phase
topic Chemical Physics
url https://arxiv.org/abs/2505.07361