We study the above-threshold ionization of atoms in intense circularly polarized laser pulses. In order to compute photoelectron energy spectra, we apply the strong-field approximation with different models for the initial state wave function. Specifically, we compare the spectra for singly ionized Barium (Ba⁺) using hydrogenic wave functions and realistic one-particle wave functions obtained by multiconfiguration Dirac–Hartree–Fock computations, respectively. As a particular example, we discuss the dependence of the photoelectron spectra on the magnetic quantum number m of the initial state and we reproduce the well known m-selectivity in strong-field ionization. Here, we show that the photoelectron spectra exhibit noticeable differences for the two models of the initial state and that the m-selectivity is enhanced when realistic wave functions are used. We conclude that the description of strong-field processes within the strong-field approximation will benefit from a realistic description of the initial atomic state.

我们研究了强圆偏振激光脉冲中原子的阈值以上电离。为了计算光电子能谱，我们对初始状态波函数应用了不同模型的强场近似。具体来说，我们分别使用氢离子波函数和通过多配置Dirac–Hartree–Fock计算获得的实际单粒子波函数比较单电离钡（Ba ⁺）的光谱。作为一个特定的例子，我们讨论了光电子光谱对初始状态的磁量子数m的依赖性，并重现了众所周知的m-强电场电离中的选择性。在这里，我们表明，对于两种初始状态模型，光电子谱显示出显着差异，并且当使用逼真的波函数时，m选择性得到了增强。我们得出结论，在强场近似中对强场过程的描述将受益于对初始原子态的现实描述。