Sensitivity of strong-field double ionization to the initial ensembles in circularly polarized laser fields

Abstract

Using the classical ensemble model, we investigate the sensitivity of double ionization in circularly polarized laser fields to the initial ensembles that are generated for an Ar atom with a definite total angular momentum. The numerical results show that the double-ionization probability in the counter-rotating case, where the electrons initially rotate against the laser field, can be much higher than that in the corotating case, where the electrons rotate with the laser field. By analyzing the energy distributions of double-ionized electrons versus time, we find that, for the counter-rotating case, the ionization of the second electron occurs much earlier than in the corotating case, and the first ionization can leave the $\mathrm{Ar}{}^{+}$ ion in a higher energy state, which can increase the second ionization probability. These results indicate that nonadiabatic effects can play an important role in double-ionization dynamics.