Photoionization of H2+ beyond the dipole approximation with zeptosecond time resolution

We numerically simulate the photoionization of a hydrogen molecular ion exposed to a monochromatic extreme ultraviolet laser field beyond the dipole approximation. In such a diatomic system, the laser field reaches the two nuclei at different instants, adding extra phase on the ionization events from two nuclei and resulting in the shift of the angular maxima in the photoelectron momentum distribution. In the limit of the infinite internuclear distance, the double-slit interference scenario can be adopted to explain the simulated photoelectron momentum distribution. However, when the internuclear distance is as short as 1 A, the electron distributes more in the center of the molecule, and the photoelectron momentum distribution carries the single-slit diffraction character. The extracted birth time delay of photoemission from two nuclei is about a few hundred of zeptoseconds, which is similar to the experimental measurement in H-2 [Grundmann et al., Science 370, 339 (2020)].

Automated summary

In this study, numerical simulations were conducted on the photoionization of a hydrogen molecular ion exposed to a monochromatic extreme ultraviolet laser field beyond the dipole approximation. It was found that at short internuclear distances, electrons are more concentrated in the center of the molecule and exhibit single-slit diffraction characteristics. The extracted birth time delay of photoemission from two nuclei is on the order of a few hundred zeptoseconds, consistent with experimental measurements in H-2.