Angle-resolved studies of XUV-IR two-photon ionization in the RABBITT scheme
Angle-resolved studies of XUV-IR two-photon ionization in the RABBITT scheme
复制标题
DOI：
10.1088/1361-6455/ab9f0d
复制
发表时间：
2020-09-28
影响因子：
1.6
通讯作者：
Dowek, D.
中科院分区：
文献类型：
--
作者：
Joseph, J.;Holzmeier, F.;Dowek, D.
通过双光子跃迁干涉重建阿秒跳动 (RABBITT) 是研究原子和分子光电离时间延迟的成熟技术。它最近已扩展到角度分辨研究，获取束缚连续谱和连续谱-连续谱跃迁内阿秒光电子发射动力学的多种指纹可观测值。在这项工作中，我们研究了与 RABBITT 边带信号相关的 I(SB)(theta,tau) 双光子光电子角分布 (PAD) 的一般形式，作为发射角 theta 的函数，以及 XUV 阿秒脉冲串和 RABBITT 方案中起作用的红外 (IR) 修整场之间的延迟 tau。依靠勒让德多项式的展开式，PAD 是根据一组缩减的系数来综合的，这些系数充分描述了其静态（与 tau 无关）和动态（与 tau 相关）分量，并使我们能够检索表征 PAD 的任何可观察到的特征。这个统一的框架简化了不同实验或理论数据集之间的比较，并强调了一些可观测值如何依赖于实验条件。除了模型分析之外，我们还报告了 Ar(3p(6)) 和 Ne(2p(6)) 的 thenp 价轨道的角度分辨 RABBITT 直接电离的新结果，该结果在新的 Attolab 设施中采用电子-离子符合动量谱。在这种情况下，合成 PAD 的九个系数进一步与过渡偶极子矩阵元素的幅度和相位相关联，从而提供了理论预测的基本测试。 Ar 和 Ne 在探索的低能区域中发现了相似点和差异，该区域比电离阈值高出 20 eV，其中电子动力学对电子相关性最敏感。对这些结果的进一步解释将受益于与先进的多体理论模拟的比较。
Reconstruction of attosecond beating by interference of two-photon transitions (RABBITT) is an established technique for studying time-delay in photoionization of atoms and molecules. It has been recently extended to angle-resolved studies, accessing diverse fingerprint observables of the attosecond photoemission dynamics within the bound-continuum and continuum-continuum transitions. In this work, we address the general form of theI(SB)(theta,tau) two-photon photoelectron angular distributions (PADs) associated to the RABBITT sideband signal, as a function of the emission angle theta, and the delay tau between the XUV attosecond pulse train and the infrared (IR) dressing field at play in the RABBITT scheme. Relying on the expansion in Legendre polynomials, the PAD is synthesized in terms of a reduced set of coefficients which fully describe both its static (tau-independent) and dynamic (tau-dependent) components and enables us to retrieve any observable characterizing the PAD. This unified framework streamlines the comparison between different experimental or theoretical data sets and emphasizes how some observables depend on the experimental conditions. Along with the modelled analysis, we report new results of angle-resolved RABBITT direct ionization of thenp valence orbital of Ar(3p(6)) and Ne(2p(6)), employing electron-ion coincidence momentum spectroscopy at the new Attolab facility. In this case, the nine coefficients synthesizing the PAD are further linked to the magnitude and phase of the transition dipole matrix elements, providing a fundamental test of theoretical predictions. Similarities and differences are found between Ar and Ne in the explored low energy region, up to 20 eV above the ionization threshold, where the electron dynamics is most sensitive to electronic correlation. Further interpretation of these results would benefit from a comparison with advanced many-body theoretical simulations.