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arXiv 1012.5334physics.atom-ph
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绝热近似在强Laser场中单电子和双电子现象中的应用

Applications of Adiabatic Approximation to One- and Two-electron Phenomena in Strong Laser Fields

Denys Bondar

摘要:

绝热近似是描述由低频激光辐射引起的现象的自然方法,因为激光频率与原子或分子的特征频率的比率是一个小参数。由于这项工作的主要目的是研究电离现象,因此必须采用可以解释从束缚态到连续谱转变的绝热近似版本。尽管在这方面做了大量的工作,但缺乏一个普遍接受的绝热方法来研究束缚-自由跃迁。因此,基于Savichev的修改的绝热近似[Sov.物理JETP 73,803(1991)],我们首先推导出手头问题的绝热近似的最方便形式。所得到的结果与准经典近似和其他以前的调查的连接进行了讨论。然后,将这种绝热近似应用于低频强激光场中原子的单电子电离和非顺序双电离。单电子分子电离也进行了研究。本文基于P. D.法隧道掘进的几何方法。希斯洛普和我。M.《回忆录》(Memoir. AMS 78,No.399(1989)]中,我们引入了超前隧道掘进轨迹的概念。然后证明了分子隧穿电离的单个活性电子模型的主导隧穿轨迹(即,其中分子势由单电子多中心势建模的理论)在短程相互作用的情况下是线性的,而在长程相互作用的情况下是“几乎”线性的。结果提出了正式和物理直观的水平。物理意义的证明声明进行了讨论。

英文摘要:

The adiabatic approximation is a natural approach for the description of phenomena induced by low frequency laser radiation because the ratio of the laser frequency to the characteristic frequency of an atom or a molecule is a small parameter. Since the main aim of this work is the study of ionization phenomena, the version of the adiabatic approximation that can account for the transition from a bound state to the continuum must be employed. Despite much work in this topic, a universally accepted adiabatic approach of bound-free transitions is lacking. Hence, based on Savichev's modified adiabatic approximation [Sov. Phys. JETP 73, 803 (1991)], we first of all derive the most convenient form of the adiabatic approximation for the problems at hand. Connections of the obtained result with the quasiclassical approximation and other previous investigations are discussed. Then, such an adiabatic approximation is applied to single-electron ionization and non-sequential double ionization of atoms in a strong low frequency laser field. Single-electron molecular ionization is also studied. Based on the geometrical approach to tunnelling by P. D. Hislop and I. M. Sigal [Memoir. AMS 78, No. 399 (1989)], we introduce the concept of a leading tunnelling trajectory. It is then proven that leading tunnelling trajectories for single active electron models of molecular tunnelling ionization (i.e., theories where a molecular potential is modelled by a single-electron multi-centre potential) are linear in the case of short range interactions and "almost" linear in the case of long range interactions. The results are presented on both the formal and physically intuitive levels. Physical implications of the proven statements are discussed.

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