中国激光, 2005, 32 (9): 1211, 网络出版: 2006-06-01  

二能级系统共振增强多光子电离过程的理论研究

Theoretical Investigation on the REMPI Processes of Two-Level System
作者单位
安徽师范大学原子与分子物理实验室,安徽 芜湖 241000
摘要
通过求解二能级系统含时密度矩阵元微分方程,对原子系统在共振和近共振情形下的激光共振增强多光子电离(REMPI)过程中的光电离几率进行了理论推导与分析,得到了光电离几率的解析表达式;研究了氧原子经共振态2p34p(2+1)共振增强多光子电离的电离几率与激光脉宽、激光光强及失谐量等参数的关系;给出了共振情形下电离饱和与激光脉宽和激光光强之间的关系式。计算结果表明,对于近共振情形(Δ较小),激光脉宽和强度一定时,电离几率随着失谐量的增加而减小;当失谐量一定时,光电离几率随光强的增加而增加,光强增加到一定程度时光电离几率出现饱和。对于共振情形(Δ=0),激光光强越大,电离几率随脉宽增加的幅度越大。
Abstract
Based on the time-dependent density-matrix equations of two-level system, the analytical formule of the resonance-enhanced multiphoton ionization (REMPI) probabilities of atom were obtained under the resonant and near-resonant condition. Furthermore, for the (2+1) REMPI of oxygen atom with the 2p34p as resonant state, the dependence of the ionization probability on laser intensity, pulse width and resonance detuning was discussed. At the same time, the relation of the saturation condition of REMPI to the laser intensity and the pulse width was derived. Under the near-resonant condition, the analytical results showed that the ionization probability decreased with the increase of resonance detuning with the fixed laser intensity and pulse width, and the ionization probability increased with the increase of laser intensity at the fixed resonance detuning and tended to become saturation when laser intensity was high enough. Under the resonant condition, the amplitude of the ionization probability increased rapidly with the pulse width when laser intensity increased.

汪小丽, 姚关心, 张先燚, 许新胜, 凤尔银, 季学韩, 崔执凤. 二能级系统共振增强多光子电离过程的理论研究[J]. 中国激光, 2005, 32(9): 1211. 汪小丽, 姚关心, 张先燚, 许新胜, 凤尔银, 季学韩, 崔执凤. Theoretical Investigation on the REMPI Processes of Two-Level System[J]. Chinese Journal of Lasers, 2005, 32(9): 1211.

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