The use of a model potential for the calculation of atomic multiphoton ionisation probabilities

A method is developed for calculating the multiphoton ionisation probabilities of atoms based on the use of the Green's function of the optical electron, obtained with the help of the model-potential method. The compound matrix elements of perturbation theory are presented in the form of rapidly convergent hypergeometric-type series, which are easily computed. The multiphoton ionisation probabilities of alkali metals, rare gases and mercury atoms are calculated in a wide range of frequencies. The results indicate sufficient accuracy and convenience of the method developed.