Theoretical Study on the Dynamics of Molecules Under Strong Laser Field

本研究项目的目的是通过强激光场和分子间的非线性相干相互作用，为激光控制化学反应建立一个基本理论。本文主要研究了光子统计对分子时间演化的影响、多光子过程、强激光场下多能级分子的谱带理论、相干激光对分子内振动重分布的限制以及强非稳态激光场下的光解离机理。我们不仅在孤立条件下处理了分子辐射相互作用，而且在热浴存在的情况下也处理了分子辐射相互作用。通过大多数的研究项目，在强激光场下分子动力学的理论处理都没有在修饰态表示中调用摄动理论。特别是，激光相位在固定激光场的控制中起着重要的作用。在强激光场作用下，由于修饰态之间存在干涉效应，多级分子的发射多重结构不能用两能级分子的简单扩展来解释。基于核波包传播的方法，建立了非平稳强激光场下超阈值光解的理论处理。除了简单的硅原子分子离子外，多原子分子的激光控制化学反应理论由于时间的限制，未能在该计划的期限内发展起来。我们继续发展激光控制化学反应的理论，以期将其应用于分子内质子转移、异构化等化学反应。我们相信本研究项目的结果可以为激光控制化学反应的实验提供重要的线索。少

The purpose of this research project was to develop a fundamental theory toward the laser control of chemical reactions through the nonlinear, coherent interactions between molecules and strong laser fields. We were concerned with main subjects such as photon statistical effects on time evolution of molecules, bath-induced multiphoton process, spectral band theory of multi-level molecules under strong laser fields, restriction of intramolecular vibrational redistribution (IVR) by using coherent lasers, and photo dissociation mechanism under strong, nonstationary laser fields. We have treated the molecule-radiation intevactions not only under isolated condition but also in the presence of the heat bath. Through most of the research projects, theoretical treatments of dynamics of molecules under strong laser fields have been developed without invoking the perturbation theory in the dressed state representation. Especially, the laser phase has been shown to make an important role in contr … More olling IVR by using stationary laser fields. The emission multiplet structure of a multi-level molecule under strong laser field can not be interpreted in terms of the simple extension of two level molecule because of presence of interference effects between the dressed states. The theoretical treatment of photodissociation above threshold under nonstationary, strong laser field has been established based on the method of the nuclear wave packet propagation. Theory of laser-controlled chemical reaction of polyatomic molecules except simple diatoomic molecule ions, however, could not be developed within the term of this program because of the time restriction. We continue developing the theory of the laser controlling chemical reaction toward application to chemical reactions of interest such as intramolecular proton transfer, isomerization etc. We are convinced that the results obtained in this research project could provide important clue to performing experiments of the laser-controlled chemical reactions. Less