Photodetachment of F-by short laser pulses. Comparison between experiments and numerical results

Recently, angle-resolved photoelectron spectra have been measured by exposing negative F–ions to linearly or circularly polarized infrared femtosecond laser fields. We compare the experimental results with numerical calculations carried out in the framework of a Keldysh-type theory modified to account for both the time shape and the spatial inhomogeneity of the pulse. In order to account for the finite duration of the laser pulse, our results have been obtained through calculations of photodetachment probabilities. By using the saddle-point method it is possible to show that the transition amplitude may be written as a coherent sum of terms giving rise to interferences. This circumstance suggests that some particular features of the experimental results may be described in terms of quantum interferences in the time domain.