Anisotropic effects in the nondipole relativistic photoionization of hydrogen

IF 1.1 Q3 PHYSICS, MULTIDISCIPLINARY
J E Vembe, M Førre
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引用次数: 0

Abstract

In the nonrelativistic and dipole regime of multiphoton ionization, spherical symmetry in all but the polarization direction of the laser pulse ensures that directional dependency in the photoelectron spectra is limited to the laser polarization direction, with the final distribution exhibiting no asymmetry along the propagation direction of the laser. When relativistic effects and spatial dependency in the external potential are accounted for however, the addition of time dilation and radiation pressure both impose anisotropic effects. Previously we have found that nondipole effects induce a redshift in the photoelectron energy distribution, while conversely relativistic effects induce a blueshift, with the net effect of an apparent near-cancellation of the two. In this work we study these effects further. By examining photoelectron momentum distributions acquired from simulations with the time-dependent Dirac equation we propose explanatory models for both phenomena and present a simplified model of the shifts as a function of the angle relative to the propagation direction of the laser pulse. It is found that both nondipole and relativistic effects must be accounted for on an equal footing in order to correctly describe the photoelectron momentum distribution in the high-intensity regime.
氢的非极性相对论光离子化中的各向异性效应
在多光子电离的非相对论和偶极机制中,除了激光脉冲的偏振方向外,其他方向都是球面对称的,这确保了光电子能谱的方向依赖性仅限于激光偏振方向,最终分布沿激光传播方向不呈现不对称。然而,当考虑到相对论效应和外部电势的空间依赖性时,时间膨胀和辐射压力都会产生各向异性效应。在此之前,我们已经发现非偶极子效应会导致光电子能量分布的红移,而相对论效应则会导致蓝移,两者的净效应明显接近抵消。在这项工作中,我们进一步研究了这些效应。通过研究利用随时间变化的狄拉克方程模拟获得的光电子动量分布,我们提出了这两种现象的解释模型,并提出了一个简化的蓝移模型,它是相对于激光脉冲传播方向的角度的函数。我们发现,为了正确描述高强度状态下的光电子动量分布,必须平等地考虑非偶极子效应和相对论效应。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Journal of Physics Communications
Journal of Physics Communications PHYSICS, MULTIDISCIPLINARY-
CiteScore
2.60
自引率
0.00%
发文量
114
审稿时长
10 weeks
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