An extreme-ultraviolet (XUV) laser pulse consisting of harmonics of a fundamental near-infrared (NIR) laser frequency is combined with the NIR pulse to systematically study two-color photoionization of helium atoms. A time-resolved photoelectron spectroscopy experiment is carried out where energy- and angle-resolved photoelectron distributions are obtained as a function of the NIR intensity and wavelength. Time-dependent Schrödinger equation calculations are performed for the conditions corresponding to the experiment and used to extract residual populations of Rydberg states resulting from excitation by the XUV + NIR pulse pair. The residual populations are studied as a function of the NIR intensity (3.5 × 10 10 − 8 × 10 12 W cm −2 ) and wavelength (760–820 nm). The evolution of the photoelectron distribution and the residual populations are interpreted using an effective restricted basis model, which includes the minimum set of states relevant to t...

中文翻译：

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氦气的红外辅助XUV光电离中的种群转移到高角动量态

将由基本近红外（NIR）激光频率的谐波组成的极紫外（XUV）激光脉冲与NIR脉冲组合，以系统地研究氦原子的双色光电离。进行了时间分辨光电子能谱实验，其中获得了能量和角度分辨光电子分布随近红外强度和波长的变化。在与实验相对应的条件下执行与时间相关的Schrödinger方程计算，并用于提取XUV + NIR脉冲对激发产生的Rydberg状态的剩余种群。根据NIR强度（3.5×10 10-8×10 12 W cm -2）和波长（760–820 nm）的函数研究剩余种群。