Theoretical Study on the Dynamics of Molecules Under Strong Laser Field

该研究项目的目的是通过分子与强激光场之间的非线性相干相互作用来发展激光控制化学反应的基础理论。主要内容包括：光子统计效应对分子时间演化的影响、浴诱导多光子过程、多能级分子在强激光作用下的能带理论、相干激光对分子内振动重分布(IVR)的限制，以及强非稳态激光作用下的光解离机制。我们不仅在隔离条件下而且在热浴存在的情况下处理了分子-辐射相互作用。在大多数研究项目中，强激光作用下分子动力学的理论处理都是在没有引用修饰态表示中的微扰理论的情况下发展起来的。特别是激光位相在控制…中起着重要的作用通过使用固定的激光场进行更多的IVR。由于修饰态之间存在干涉效应，多能级分子在强激光作用下的发射多重态结构不能用二能级分子的简单扩展来解释。基于核波包传播方法，建立了非平稳强激光场下阈值以上光解的理论处理方法。然而，由于时间的限制，除了简单的对偶体分子离子外，激光控制多原子分子化学反应的理论不能在本项目的期限内发展起来。我们继续将激光控制化学反应的理论向分子内质子转移、异构化等感兴趣的化学反应应用方向发展。我们相信，本研究项目所获得的结果将为开展激光控制化学反应的实验提供重要线索。较少

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