Total ionization rates and ion yields of atoms at nonperturbative laser intensities

A simply modified Keldysh-Faisal-Reiss (KFR) model for the total rate of ionization of atoms in the nonperturbative domain of intensity was investigated. Predictions of the model formula were first compared with that of ab initio Floquet calculations. Following this, predictions of the present simply corrected rate formula were compared with the results of ab initio time-dependent 3D numerical simulations for the H atom. Finally, an attempt was made to apply the present rate formula to analyze 36 available experimental data sets for the single-ionization yields of noble-gas atoms He, Ne, Ar, Kr, and Xe.