Theoretical and Experimental Photoelectron Spectroscopy Characterization of the Ground State of Thymine Cation

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• 作者：Youssef Majdi ; Majdi Hochlaf ; Yi Pan ; Kai-Chung Lau ; Lionel Poisson ; Gustavo A. Garcia ; Laurent Nahon ; Muneerah Mogren Al-Mogren ; Martin Schwell
• 刊名：Journal of Physical Chemistry A
• 出版年：2015
• 出版时间：June 11, 2015
• 年：2015
• 卷：119
• 期：23
• 页码：5951-5958
• 全文大小：278K
• ISSN：1520-5215

文摘

We report on the vibronic structure of the ground state X虄²A鈥?of the thymine cation, which has been measured using a threshold photoelectron photoion coincidence technique and vacuum ultraviolet synchrotron radiation. The threshold photoelectron spectrum, recorded over 鈭?.7 eV above the ionization potential (i.e., covering the whole ground state of the cation) shows rich vibrational structure that has been assigned with the help of calculated anharmonic modes of the ground electronic cation state at the PBE0/aug-cc-pVDZ level of theory. The adiabatic ionization energy has been experimentally determined as AIE = 8.913 卤 0.005 eV, in very good agreement with previous high resolution results. The corresponding theoretical value of AIE = 8.917 eV has been calculated in this work with the explicitly correlated method/basis set (R)CCSD(T)-F12/cc-pVTZ-F12, which validates the theoretical approach and benchmarks its accuracy for future studies of medium-sized biological molecules.