Photoionization indicators of optical mixing of different-parity degenerate Rydberg states - art. no. 023413

We discuss a photoionization version of the photoexcitation model of Corles s and Stroud [Phys. Rev. Lett. 79, 637 (1997)]. In the photoexcitation mode l, a np hydrogenic state of n much greater than 1 was excited from the grou nd 1s state and the excited population was allowed to migrate to other angu lar momentum states within the one n only due to strongly nonresonant elect ric-dipole \Delta n\ = 0, \Delta l\ = 1 Rydberg-to-Rydberg couplings. When, as is the essence of the photoexcitation model, the same one n-manifold ap proximation is made in the model of high-n Rydberg-state photoionization, a number of interesting photoionization effects are obtained. Among them, th e most spectacular seems to be the emission of photoelectrons in the "forbi dden" directions and the suppression of ionization when compared to the Fer mi golden rule predictions. However, we show on the basis of an approximate analysis that these photoionization effects can be strongly diminished whe n additional n manifolds around the selected one are included in the model. Thus, we conclude that the one n-manifold approximation overestimates resu lts when applied to the problem of high-n Rydberg-state photoionization.