S_2O^-自由基光电子能谱的Franck-Condon分析

Franck-condon simulation of photoelectron spectroscopy of S_2O^-radical

本文考虑多振动模混合和热带效应,凭借谐振子模型,推得计算两维-四振动模Franck-Condon重叠积分的解析表示,且应用于S_2O^-自由基光电子能谱的理论研究.对于S_2O(X^1A')—S_2O^-(X^2A")光脱附过程,结合分子轨道从头算和密度泛函理论,计算Franck-Condon因子,从而得到电子跃迁振动谱线的相对强度,理论上得到的光电子能谱与实验上观测到的能谱达到较好的一致;进一步在光谱模拟过程中,拟合实验能谱得到可靠的负离子自由基S_2O^-电子态(X^2A")的几何结构参数:键长R(SS)=2.008±0.005A和R(SO)=1.519±0.005 A.

A more general analytical expression for the calculation of the two-dimensional four-mode Franck-Condon overlap integrals was derived straightforwardly on the base of harmonic oscillator approximation under the mode mixing and hot band effects. This new analytical expression was applied to study the photoelectron spectra of S2O￣. Geometry optimizations and harmonic vibrational frequency calculations have been performed on the 1A′ state of S2O and 2A″ state of S2O￣. Franck-Condon analyses and spectral simulations were carried out on the S2O（ 1A′） – S2O￣（ 2A″） photodetachment processes. The spectral simulations of vibrational structures based on the computed Franck-Condon factors are in excellent agreement with the observed spectra. In addition, the equilibrium geometric parameters of the 2A″ state of S2O￣ were obtained in the spectral simulations： bond lengths R（SS） =2.008 ？＋/-0.005？ and R（SO）=1.519＋/-0.005A.