Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
J Phys Chem A. 2012 Nov 26;116(46):11219-27. doi: 10.1021/jp3052054. Epub 2012 Aug 15.
Nonresonant optimal control simulation is applied to a CO molecule to design two-color phase-locked laser pulses (800 nm + 400 nm) with the aim of orienting the molecule under the field-free condition. The optimal pulse consists of two subpulses: the first subpulse aligns the molecule and the second one orients it. The molecular alignment induced by the first subpulse considerably enhances the degree of orientation, the value of which is close to an ideal value at temperature T = 0 K. To confirm the effectiveness of this alignment-enhanced orientation mechanism, we adopt a set of model Gaussian pulses and calculate the maximum degrees of orientation as a function of the delay time and the intensity. In finite-temperature (T = 3.0 K and T = 5.0 K) cases, although the alignment subpulse can improve the degree of orientation, the control achievement decreases with temperature rapidly; this decrease can be attributed to the initial-state-dependent (phase-shifted) rotational wave packet motion.
非共振最优控制模拟被应用于 CO 分子，以设计双色锁相激光脉冲（800nm + 400nm），目的是在无场条件下对分子进行取向。最优脉冲由两个子脉冲组成：第一个子脉冲使分子排列，第二个子脉冲使分子取向。第一个子脉冲诱导的分子排列极大地增强了取向的程度，其值在温度 T=0K 时接近理想值。为了证实这种增强取向机制的有效性，我们采用了一组模型高斯脉冲，并计算了最大取向程度作为延迟时间和强度的函数。在有限温度（T=3.0K 和 T=5.0K）情况下，尽管排列子脉冲可以提高取向程度，但控制效果随温度迅速下降；这种下降归因于初始态相关（相移）的转动波包运动。
