原子势对阈上电离平台的影响

摘要

We investigate theoretically the influence of the long-range and short-range potentials on the plateau structure of the above threshold ionization. In a considerable range of laser parameter, the above threshold ionization spectra of the atoms in the long-range potential always exhibit a clear double-plateau structure; as for the atoms with a short-range potential, the boundary of the double-plateau in photoelectron spectra is no longer clear, and with the decrease of laser intensity, it transits from the double-plateau to the single-plateau gradually. The numerical simulation based on classical analysis and quantum mechanics illustrates that in different model potentials, the distinction of ionization rates as well as the difference of the electronic elastic rescattering cross-sections results in the difference of plateau structures. In addition, the influence of intensity distribution of laser pulse on the phenomenon is discussed.%　　本文从理论上分别研究了长程和短程原子势对阈上电离光电子谱平台结构的影响。发现在相当大的激光参数范围内，长程势的阈上电离谱总是呈现出清晰的双平台结构；对于短程势，阈上电离谱双平台的界限不再清晰，随着入射激光强度的减小，逐渐从双平台过渡到单平台。基于经典分析和量子力学数值模拟，阐明了在不同模型势下，电离速率的差别和再散射电子弹性碰撞截面的不同导致了上述平台结构的差异。此外，还讨论了激光脉冲空间强度分布对这一现象的影响。