标题： 氢原子在非单色激光场中的共振三光子电离 显示英文标题

标题： Resonant 3--photon ionization of hydrogenic atoms by non-monochromatic laser field

摘要： 我们对氢原子基态在非单色激光场中的两步三光子电离过程，$1S \stackrel{2\hbar \omega}{\longrightarrow}2S \stackrel{\hbar \omega}{\longrightarrow}\epsilon P $，进行了电离概率和线形计算。 在三级模型的框架下，考虑了所有涉及状态的{\it AC Stark}位移和非零电离率，以及激光信号的空间和时间不均匀性。 与通常的微扰技术不同，原子态的时间演化是通过直接数值求解耦合的时间依赖非齐次微分方程组来模拟的，这等价于适当的非定态薛定谔方程。 对于在新实验中用于测量缪子中$1S-2S$能量间隔的脉冲激光场的典型参数，得到了特定的数值结果。 所揭示的光电子电离线形的位移和不对称性可能对氢原子在连续波激光场中的超高精度实验具有相关性。 显示英文摘要

摘要： We present ionization probability and line shape calculations for the two-step 3-photon ionization process, $1S \stackrel{2\hbar \omega}{\longrightarrow}2S \stackrel{\hbar \omega}{\longrightarrow}\epsilon P $, of the ground state of hydrogenic atoms in a non-monochromatic laser field with a time--dependent amplitude. Within the framework of a three--level model, the {\it AC Stark} shifts and non-zero ionization rates of all states involved were taken into account together with spatial and temporal inhomogeneities of the laser signal. In contrast with the usual perturbative technique, the time evolution of the atomic states was simulated by direct numerically solving the system of coupled time--dependent inhomogeneous differential equations, being equivalent to the appropriate non-stationary Schr\"{o}dinger equation. Particular numerical results were obtained for typical parameters of the pulsed laser field that are employed in a new experiment to measure the $1S-2S$ energy separation in muonium at the Rutherford Appleton Laboratory. The shifts and asymmetries of the photoionization line shapes revealed may be of relevance for ultra-high precision experiments in hydrogen in CW laser fields.