Ionization dynamics in two-color laser fields - "phase-of-the-phase" spectroscopy and semi-classical trajectory analysis

理解强场电离动力学为物质的结构和动力学成像、粒子加速和使用强激光脉冲的新型辐射源提供了基础。与“标准”动量分辨光电子能谱相比，最近引入的“相的相”（PoP）能谱提供了关于靶特定强场电离动力学的额外信息。这个想法是记录产量的变化和它的相位滞后相对于一个双色脉冲的相对相位，提供一个增强的灵敏度上的子周期时间尺度和消除热或其他不相干的电子发射过程，否则杂波强场光电子光谱从多电子系统。我们建议在联合实验和理论的努力，POP光谱的目标属性和激光波长的依赖关系进行调查。将研究原子目标（氢、碱、稀有气体）以及有限系统（SF6、C60），以便系统地研究PoP在以下方面的前景，例如，（动态）自成像，用于增加目标复杂性。由于PoP光谱可以很容易地扩展到更长的波长，测量低电离电位的目标可以在半经典的制度。量子轨道的强大理论工具，然后适用，产生前所未有的和直观的洞察力的基础物理机制。

Understanding strong-field ionization dynamics provides the basis for structural and dynamical imaging of matter, acceleration of particles, and novel radiation sources using intense laser pulses. Compared to "standard" momentum-resolved photoelectron spectra, the recently introduced "Phase-of-the-Phase" (PoP) spectroscopy gives additional information about the target-specific strong-field ionization dynamics. The idea is to record the change in the yield and its phase lag with respect to the relative phase of a two-color pulse, providing an enhanced sensitivity on a subcycle timescale and eliminating thermal or other incoherent electron emission processes that otherwise clutter strong-field photoelectron spectra from multi-electron systems. We propose to investigate in a joint experimental and theoretical effort the dependencies of PoP spectra on target properties and laser wavelength. Atomic targets (hydrogen, alkalies, rare gases) as well as finite systems (SF6, C60) will be studied in order to systematically investigate the prospects of PoP as regards, e.g., (dynamical) self-imaging, for increasing target complexity. Since PoP spectroscopy can be easily extended towards longer wavelengths, measurements on low-ionization-potential targets can be performed within the semi-classical regime. The powerful theoretical tool of quantum trajectories is then applicable, yielding unprecedented and intuitive insight into the underlying physical mechanisms.