Theory of bound-free transitions: extension of the pole approximation

Summary form only given. We have developed a general theory of single-photon bound-free transitions, which takes into account all the states of the quantum system of interest and treats the rotating- and counterrotating-wave terms on equal footing. With the help of the smoothed-dynamics approximation (SDA), which holds until the laser field is much weaker than the intramolecular field, a closed analytical result for the Laplace transform of the initial-state amplitude has been obtained. To perform the inverse Laplace transform, the pole approximation, extended to obtain higher-order corrections, has been employed