用强场近似计算原子分子电离率规范依赖问题研究

项目名称： 用强场近似计算原子分子电离率规范依赖问题研究

项目编号： No.11274149

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 数理科学和化学

项目作者： 马凤才

作者单位： 辽宁大学

项目金额： 81万元

中文摘要： 原子和分子在强激光场中电离过程是研究电磁场与物质相互作用的许多重要过程的基础。描写这一过程最具影响、被广泛应用的是Keldysh, Faisal and Reiss创立的强场近似理论（KFR）。依据原子与激光场相互作用的哈密顿量形式不同，强场近似分成长度规范理论和速度规范理论两种。电磁相互作用是规范不变的，用不同规范的理论计算的原子分子电离率应该相同。然而，KFR用于计算实际过程，不同规范的理论却得出不同的结果，某些情况甚至有数量级的差别。因而，深入研究KFR规范依赖问题既是理论发展的需要，也是正确理解原子与电磁场相互作用实验数据所急需。本项目以KFR所做的各种近似为切入点，逐个研究它们对不同规范的理论所引起的计算结果的差异。结合新的实验数据，借鉴电磁场中原子束缚-束缚态跃迁规范相关问题的研究，寻找用KFR计算原子跃迁率依赖规范选择的主要原因，探索改进理论的途径,使理论更好的解释实验。

中文关键词： 强场近似；多光子电离；规范不变性；隧道电离；激光场与物质相互作用

英文摘要： Ionization process of atom and molecule in intense laser field is the foundation of many important process of interaction between electromagnetic fields and material. To describe this process, the most influential and widely used theory is the strong field approximation developed by Keldysh-Faisal-Reiss(KFR). Based on the different Hamiltonian form of the laser-atom interaction, the strong field approximation is divided into the length-gauge and the velocity-gauge theories. The atomic and molecular ionization rates are expected to be same in the different gauge calculations, since the electromagnetic interaction is gauge invariant. However, the different results have been obtained when different gauge theories are used in practical calculations, even there are several orders of magnitude discrepancy in some cases. Therefore, it is necessary to deeply investigate the gauge dependence problem of KFR, not only for the theoretical development but also for the correct understanding of the experiment results of interaction between atom and electromagnetic field. In this proposal, the differences of calculated results introduced by employing different gauge theories are implemented, which are based on the variety of approximation of KFR theory. Combining with new experimental results and the studies related to the gaug

英文关键词： strong field approximation；multiphoton ionization；gauge invariance；tunnel ionization；interaction between laser field and materials