An Heesun, Choi Heechol, Lee Yoon Sup, Baeck Kyoung Koo
Department of Chemistry, Gangneung-Wonju National University, Gangwon-Do 210-702 (Republic of Korea).
Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Republic of Korea).
Chemphyschem. 2015 May 18;16(7):1529-34. doi: 10.1002/cphc.201500060. Epub 2015 Mar 10.
The photodissociation dynamics of thiophenol (PhSH) excited to the 1(1) ππ* state was investigated by time-dependent quantum wavepacket propagation within two-dimensional (2D) space consisting of the S-H bond and -SH torsion. We systematically studied the dependence of the branching ratio (Ã/X(~)) between the two electronic states of the phenylthiyl radical (PhS(.) ) on several factors of the 2D potential energy surfaces (PESs). The effect of a reduced initial barrier to the first ππ*/πσ* conical intersection (CI) was found to be marginal, whereas the effects of a reduced torsional barrier of -SH on the excited ππ* state and the mitigated slope of the πσ* PES between the first (ππ*/πσ*) and the second (πσ*/S0 ) CIs were noticeable. The effect of the slope on the branching ratio has never been previously noticed. It was shown that the branching ratio can be sufficiently above unity without pre-excitation of the torsion mode of -SH, which has been assumed so far.
通过在由S-H键和-SH扭转组成的二维（2D）空间内进行含时量子波包传播，研究了激发到1(1) ππ态的苯硫酚（PhSH）的光解离动力学。我们系统地研究了苯硫基自由基（PhS(.) ）的两个电子态之间的分支比（Ã/X(~)）对二维势能面（PESs）的几个因素的依赖性。发现初始势垒降低对第一个ππ/πσ锥形交叉点（CI）的影响很小，而-SH在激发态ππ上的扭转势垒降低以及第一个（ππ*/πσ*）和第二个（πσ*/S0 ）CI之间πσ* PES的斜率减小的影响是显著的。斜率对分支比的影响以前从未被注意到。结果表明，分支比可以在没有-SH扭转模式预激发的情况下充分大于1，而到目前为止一直是这样假设的。
