We have theoretically investigated the modulation structures of the excited-state population of an argon atom exposed to a linearly polarized 800-nm laser pulse in the tunneling region. The numerical result identifies a nearly opposite phase modulation structure between the low-lying n = 4–7 states and over all higher \(n>7\) states. This phase-dependent alternating population phenomenon is found to be related to the periodic channel-closing effect that results from ac-Stark-shifted multiphoton resonances. Moreover, the angular momentum states attributed to different parities have a similar alternating effect, which confirms a multiphoton process in the tunneling region. We introduce a mechanism of two-photon \(\Lambda \)-type Raman transitions involving Rydberg and continuum states with a simultaneous redistribution of states to account successfully for this observed out-of-phase angular momentum state population.

我们从理论上研究了隧穿区域中暴露于线偏振800 nm激光脉冲的氩原子激发态种群的调制结构。数值结果表明，在较低的n = 4-7状态与所有较高的\（n> 7 \）状态之间几乎相反的相位调制结构。已发现这种与相位有关的交替种群现象与由ac-Stark位移的多光子共振引起的周期性通道关闭效应有关。此外，归因于不同奇偶性的角动量状态具有相似的交替效应，这证实了隧穿区域中的多光子过程。我们介绍了双光子\（\ Lambda \）的机制-型拉曼跃迁，涉及里德堡和连续体状态，同时进行状态的重新分配，以成功解释这种观察到的异相角动量状态总体。