Multiple ionisation by intense laser pulses in the independent-electron model: application to xenon

The Hartree independent-electron model is applied to the evaluation of the relative numbers of multicharged Xe ion species produced by intense laser pulses. Single- electron ionisation probabilities are constructed from a Keldysh-like formula containing adjustable parameters to give best fits to data at 6.42, 2.33, 1.17 and 0.117 eV photon energies. The spatial intensity distribution of the laser beam is folded in. Overall satisfactory fits to the data over this wide wavelength range with physically reasonable parameters confirm the validity of the model. The time evolution of the various states of ionisation during the pulse is qualitatively similar to the sequential ionisation picture.