Chelkowski Szczepan, Bandrauk André D, Corkum Paul B
Laboratoire de Chimie Théorique, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1.
Joint Attosecond Science Laboratory of the National Research Council and the University of Ottawa, 100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6.
Phys Rev Lett. 2014 Dec 31;113(26):263005. doi: 10.1103/PhysRevLett.113.263005.
We investigate photon-momentum sharing between an electron and an ion following different photoionization regimes. We find very different partitioning of the photon momentum in one-photon ionization (the photoelectric effect) as compared to multiphoton processes. In the photoelectric effect, the electron acquires a momentum that is much greater than the single photon momentum ℏω/c [up to (8/5) ℏω/c] whereas in the strong-field ionization regime, the photoelectron only acquires the momentum corresponding to the photons absorbed above the field-free ionization threshold plus a momentum corresponding to a fraction (3/10) of the ionization potential Ip. In both cases, due to the smallness of the electron-ion mass ratio, the ion takes nearly the entire momentum of all absorbed N photons (via the electron-ion center of mass). Additionally, the ion takes, as a recoil, the photoelectron momentum resulting from mutual electron-ion interaction in the electromagnetic field. Consequently, the momentum partitioning of the photofragments is very different in both regimes. This suggests that there is a rich, unexplored physics to be studied between these two limits which can be generated with current ultrafast laser technology.
我们研究了在不同光电离机制下电子与离子之间的光子动量分配。我们发现，与多光子过程相比，单光子电离（光电效应）中的光子动量分配有很大不同。在光电效应中，电子获得的动量远大于单个光子的动量ℏω/c[高达(8/5)ℏω/c]，而在强场电离机制中，光电子仅获得对应于高于无场电离阈值吸收的光子的动量，再加上对应于电离势Ip的(3/10)的一部分的动量。在这两种情况下，由于电子与离子质量比很小，离子几乎获得了所有吸收的N个光子的全部动量（通过电子-离子质心）。此外，离子作为反冲，获得了电磁场中电子-离子相互作用产生的光电子动量。因此，在这两种机制中，光碎片的动量分配非常不同。这表明在这两个极限之间存在丰富的、尚未探索的物理现象有待用当前的超快激光技术进行研究。
