Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany.
Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, D-22607 Hamburg, Germany.
Phys Rev Lett. 2019 Feb 22;122(7):073001. doi: 10.1103/PhysRevLett.122.073001.
Time delays for atomic photoemission obtained in streaking or reconstruction of attosecond bursts by interference of two-photon transitions experiments originate from a combination of the quantum mechanical Wigner time and the Coulomb-laser coupling. While the former was investigated intensively theoretically as well as experimentally, the latter attracted less interest in experiments and has mostly been subject to calculations. Here, we present a measurement of the Coulomb-laser coupling-induced time shifts in photoionization of neon at 59.4 eV using a terahertz (THz) streaking field (λ=152 μm). Employing a reaction microscope at the THz beamline of the free-electron laser in Hamburg (FLASH), we have measured relative time shifts of up to 70 fs between the emission of 2p photoelectrons (∼38 eV) and low-energetic (<1 eV) photoelectrons. A comparison with theoretical predictions on Coulomb-laser coupling reveals reasonably good agreement.
通过双光子跃迁实验的干涉条纹或重建阿秒脉冲，获得的原子光发射的时间延迟来源于量子力学的维格纳时间和库仑-激光耦合的组合。虽然前者在理论和实验上都得到了深入的研究，但后者在实验中引起的兴趣较少，并且主要是通过计算来研究。在这里，我们使用太赫兹（THz）条纹场（λ=152μm），在 59.4eV 的氖光电离中测量了库仑-激光耦合引起的时间位移。利用汉堡自由电子激光 THz 光束线（FLASH）上的反应显微镜，我们已经测量了 2p 光电子（约 38eV）和低能（<1eV）光电子发射之间的最大 70fs 的相对时间延迟。与库仑-激光耦合的理论预测进行比较，结果表明两者吻合得相当好。
