We investigate the intensity- and species-dependent strong-field ionization of alkali metal atoms; sodium, potassium, rubidium and caesium; by intense, few-cycle laser pulses in the short-wave infrared (sw-IR) regime at 1800 nm. The low ionization potential, I p , of these atoms allows us to scale the interaction and study the tunneling regime at sw-IR wavelengths using low intensities and pulse energies. Measurements of above-threshold ionization spectra in the alkali species exhibit distinct differences to rare gas spectra at 800 and 1800 nm. However, pairing the low ionization potential of these atoms with longer wavelengths results in the reemergence of some well-know features of nobel gas spectra in the visible, e.g., the plateau. Our focus lies on the comparison of high-energy rescattered electron yield among the different alkali species. The highly unfavorable plateau scaling known from rare gases at longer wavelengths is successfully circumvented by swit...

中文翻译：

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短波红外条件下弱结合原子的依赖于物种的隧穿电离

我们研究了碱金属原子的强度和物种相关的强场电离。钠，钾，id和铯；通过短波红外（sw-IR）方式在1800 nm处发出强烈的，短周期的激光脉冲。这些原子的低电离能I p使我们能够缩放相互作用，并使用低强度和脉冲能量在sw-IR波长下研究隧穿机制。碱性物质中阈值以上电离光谱的测量结果与稀有气体光谱在800和1800 nm处显示出明显的差异。但是，将这些原子的低电离势与更长的波长配对会导致在可见光（例如高原）中出现诺贝尔气体光谱的一些众所周知的特征。我们的重点在于比较不同碱物种之间的高能散射电子产率。