Jiménez-Galán Álvaro, Argenti Luca, Martín Fernando
Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain, EU.
Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain, EU and Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Cantoblanco 28049 Madrid, Spain, EU.
Phys Rev Lett. 2014 Dec 31;113(26):263001. doi: 10.1103/PhysRevLett.113.263001. Epub 2014 Dec 24.
We present a theoretical study of the photoelectron attosecond beating due to interference of two-photon transitions in the presence of autoionizing states. We show that, as a harmonic traverses a resonance, both the phase shift and frequency of the sideband beating significantly vary with photon energy. Furthermore, the beating between two resonant paths persists even when the pump and the probe pulses do not overlap, thus providing a nonholographic interferometric means to reconstruct coherent metastable wave packets. We characterize these phenomena by means of a general analytical model that accounts for the effect of both intermediate and final resonances on two-photon processes. The model predictions are in excellent agreement with those of accurate ab initio calculations for the helium atom in the region of the N=2 doubly excited states.
我们对存在自电离态时双光子跃迁干涉导致的光电子阿秒拍频进行了理论研究。我们表明，当一个谐波穿过共振时，边带拍频的相移和频率都随光子能量显著变化。此外，即使泵浦脉冲和探测脉冲不重叠，两条共振路径之间的拍频仍然存在，从而提供了一种非全息干涉测量手段来重建相干亚稳态波包。我们通过一个通用的分析模型来描述这些现象，该模型考虑了中间共振和最终共振对双光子过程的影响。对于氦原子在(N = 2)双激发态区域，该模型预测与精确的从头计算结果非常吻合。
