Circular dichroism in atomic resonance-enhanced few-photon ionization
Circular dichroism in atomic resonance-enhanced few-photon ionization
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DOI：
10.1103/physreva.103.053125
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发表时间：
2021-03
影响因子：
2.9
通讯作者：
A. H. N. C. De Silva;T. Moon;K. Romans;B. Acharya;S. Dubey;K. Foster;O. Russ;C. Rischbieter;N. Douguet;K. Bartschat;D. Fischer
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文献类型：
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作者：
A. H. N. C. De Silva;T. Moon;K. Romans;B. Acharya;S. Dubey;K. Foster;O. Russ;C. Rischbieter;N. Douguet;K. Bartschat;D. Fischer
研究了在665-920 nm波长范围内，在左旋或右旋圆偏振的飞秒光脉冲作用下，极化2p(m=+1)态锂原子的少光子电离。我们考虑了与初始电子电流密度同向旋转或反向旋转时，电fi场的电离进行得更有利。发现了强烈的不对称性，并用圆二色谱(CD)对其进行了定量分析。虽然测量的CD值的强度依赖性在整个研究范围内相当弱，但观察到对入射辐射的中心波长的非常强的敏感性。虽然同向旋转的情况总体上占上风，但由于2p-3的S共振跃迁只能由反向旋转的fi场驱动，因此在800 nm附近的反向旋转几何构型受到强烈的青睐。这些观察到的特征提供了对光-原子相互作用的螺旋度依赖的洞察，以及通过偏振选择共振增强对原子少光子电离中电子发射的可能控制。
We investigate few-photon ionization of lithium atoms prepared in the polarized 2 p ( m = +1) state when subjected to femtosecond light pulses with left- or right-handed circular polarization at wavelengths between 665 nm and 920 nm. We consider whether ionization proceeds more favorably for the electric field co- or counter-rotating with the initial electronic current density. Strong asymmetries are found and quantitatively analyzed in terms of “circular dichroism” ( CD ). While the intensity dependence of the measured CD values is rather weak throughout the investigated regime, a very strong sensitivity on the center wavelength of the incoming radiation is observed. While the co-rotating situation overall prevails, the counter-rotating geometry is strongly favored around 800 nm due to the 2 p -3 s resonant transition, which can only be driven by counter-rotating fields. The observed features provide insights into the helicity dependence of light-atom interactions, and on the possible control of electron emission in atomic few-photon ionization by polarization-selective resonance enhancement.