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Title:Probing the vibrational spectroscopy of the deprotonated thymine radical by photodetachment and state-selective autodetachment photoelectron spectroscopy via dipole-bound states
Author(s):Zhu, Guo-Zhu
Contributor(s):Wang, Lai-Sheng; Huang, Dao-Ling
Subject(s):Spectroscopy in Traps
Abstract:Deprotonated thymine can exist in two different forms, depending on which of its two N sites is deprotonated: N1[T-H]$^-$ or N3[T-H]$^-$. Here we report a photodetachment study of the N1[T-H]$^-$ isomer cooled in a cryogenic ion trap and the observation of an excited dipole-bound state\footnote{D. L. Huang, H. T. Liu, C. G. Ning, G. Z. Zhu and L. S. Wang, $\it{Chem. Sci.}$, $\bf{6}$, 3129-3138 (2015)}. Eighteen vibrational levels of the dipole-bound state are observed, and its vibrational ground state is found to be 238 $\pm$ 5 \wn below the detachment threshold of N1[T-H]$^-$. The electron affinity of the deprotonated thymine radical (N1[T-H]$^.$) is measured accruately to be 26 322 $\pm$ 5 \wn (3.2635 $\pm$ 0.0006 eV). By tuning the detachment laser to the sixteen vibrational levels of the dipole-bound state that are above the detachment threshold, highly non-Franck-Condon resonant-enhanced photoelectron spectra are obtained due to state- and mode-selective vibrational autodetachment. Much richer vibrational information is obtained for the deprotonated thymine radical from the photodetachment and resonant-enhanced photoelectron spectroscopy. Eleven fundamental vibrational frequencies in the low-frequency regime are obtained for the N1[T-H]$^.$ radical, including the two lowest-frequency internal rotational modes of the methyl group at 70 $\pm$ 8 \wn and 92 $\pm$ 5 \wn.
Issue Date:2016-06-22
Publisher:International Symposium on Molecular Spectroscopy
Genre:Conference Paper/Presentation
Rights Information:Copyright 2016 by the authors
Date Available in IDEALS:2016-08-22

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