標題: Excited State ab Initio and Franck-Condon Simulation of S-1 -> S-0 Fluorescence Excitation Spectra of p-, m-, and o-Difluorobenzenes
作者: Yang, Qianliu
He, Rongxing
Shen, Wei
Li, Huabing
Li, Ming
Zhu, Chaoyuan
Lin, Sheng Hsien
應用化學系
應用化學系分子科學碩博班
Department of Applied Chemistry
Institute of Molecular science
公開日期: 8-十二月-2011
摘要: Although difluorobenzenes (DFBs) are well-known organic molecules to understand the electronic structure and spectroscopy of benzene and its derivatives, few theoretical investigations have been performed to simulate their fine spectra and assign their vibrational bands. In this work, the fluorescence excitation (FEX) spectra of the first excited singlet states for three DFBs molecules (para-, meta- and ortho-difluorobenzene) were simulated by the Franck-Condon calculations with the displaced harmonic oscillator approximation plus the distorted correction. The calculated results indicated that the spectral profiles of three DFBs are primarily described by the Franck-Condon progression of their totally symmetric vibrational modes. Specifically, it is found that modes v(3) and v(8) of para-DFB, v(8) and v(9) of meta-DFB, and ortho-DFB play the most important roles in the fluorescence spectra. By taking into account the contributions of the distorted effect, we could assign most of the dominant overtones from the nontotally symmetric vibrational modes, and the results agree well with the experimental assignments. Some inferred and unassigned vibrational transitions in experiment were confirmed according to the present calculated results. In addition, in the simulated fluorescence spectra, we tentatively assigned several combination bands with relative moderate intensity and weak vibrational lines which appeared in the experimental observations but the corresponding assignments were not given. The present work reproduced satisfactorily the experimental FEX spectra of p-, m-, and o-DFBs derivatives and provided a useful method to simulate the FEX spectra of dihalogenated benzene molecules.
URI: http://dx.doi.org/10.1021/jp207051g
http://hdl.handle.net/11536/150418
ISSN: 1089-5639
DOI: 10.1021/jp207051g
期刊: JOURNAL OF PHYSICAL CHEMISTRY A
Volume: 115
起始頁: 14022
結束頁: 14033
顯示於類別:期刊論文