Schmidt H, von Vangerow J, Stienkemeier F, Bogomolov A S, Baklanov A V, Reich D M, Skomorowski W, Koch C P, Mudrich M
Physikalisches Institut, Universität Freiburg, 79104 Freiburg, Germany.
Institute of Chemical Kinetics and Combustion, Novosibirsk 630090, Russia.
J Chem Phys. 2015 Jan 28;142(4):044303. doi: 10.1063/1.4906512.
The predissociation dynamics of lithium iodide (LiI) in the first excited A-state is investigated for molecules in the gas phase and embedded in helium nanodroplets, using femtosecond pump-probe photoionization spectroscopy. In the gas phase, the transient Li(+) and LiI(+) ion signals feature damped oscillations due to the excitation and decay of a vibrational wave packet. Based on high-level ab initio calculations of the electronic structure of LiI and simulations of the wave packet dynamics, the exponential signal decay is found to result from predissociation predominantly at the lowest avoided X-A potential curve crossing, for which we infer a coupling constant VXA = 650(20) cm(-1). The lack of a pump-probe delay dependence for the case of LiI embedded in helium nanodroplets indicates fast droplet-induced relaxation of the vibrational excitation.
利用飞秒泵浦-探测光电离光谱，研究了气相中以及嵌入氦纳米液滴中的碘化锂（LiI）在第一激发A态的预解离动力学。在气相中，由于振动波包的激发和衰减，瞬态Li(+)和LiI(+)离子信号呈现出阻尼振荡。基于LiI电子结构的高精度从头算计算以及波包动力学模拟，发现指数信号衰减主要是由最低的避免交叉X-A势能曲线处的预解离导致的，据此我们推断耦合常数VXA = 650(20) cm(-1)。对于嵌入氦纳米液滴中的LiI情况，泵浦-探测延迟依赖性的缺乏表明液滴诱导的振动激发快速弛豫。
