Ionization rates and harmonic generation for H interacting with laser pulses of and peak intensities in the range -

Abstract

We applied the state-specific expansion approach (SSEA) to the solution of the time-dependent Schrödinger equation describing the interaction of H with laser pulses of and peak intensities , , and , and computed ionization rates and high-order harmonic spectra. For the first three cases, our results are compared with those of Krause and co-workers (Krause J L, Schafer K J and Kulander K C 1992 A 45 4998) who employed the grid method. Whereas for convergence difficulties were reported for the grid method, no such difficulties were found for the SSEA. Given this fact, we tackled the problem of computing the harmonic spectrum for , the most difficult case treated thus far. This spectrum shows a cut-off at the 65th harmonic and an extended plateau containing low-intensity harmonics up to the 181st. The ionization rate is while at the end of the pulse 19.5% of the system is in the 1s ground state and 2.6% in the bound states up to n = 20, l = 19.