Influence of the phase of the electromagnetic field on the processes of charge transfer and ionization in laser-assisted collisions of protons with hydrogen atoms

We perform a theoretical and computational study of laser-assisted collisions of protons with hydrogen atoms. The incident proton energy is equal to 0.25 keV, and the laser field is linearly polarized with the frequencies in the infrared ( ω = 0.01 a.u.) and extreme ultraviolet ( ω = 2 a.u.) regions of the spectrum. For the infrared laser field, we use the peak intensities 1 × 10 12 W/cm 2 and 1 × 10 13 W/cm 2 while for the extreme ultraviolet field the peak intensity is equal to 5 × 10 14 W/cm 2 . Our study is focused on the influence of the phase of the laser field on the ionization and charge transfer probabilities. For the infrared laser field and small impact parameters (0.125- - 1.5 a.u), our results demonstrate a strong dependence of the charge transfer and ionization probabilities on the phase of the field at the moment when the proton approaches the hydrogen atom most closely. On the contrary, for the field in the extreme ultraviolet region, the charge transfer and ionization probabilities do not depend on the phase of the field irrespective of the impact parameter value. Graphical abstract