We discuss a photoionization version of the photoexcitation model of Corless and Stroud [Phys. Rev. Lett. 79, 637 (1997)]. In the photoexcitation model, a np hydrogenic state of n>>1 was excited from the ground 1s state and the excited population was allowed to migrate to other angular momentum states within the one n only due to strongly nonresonant electric-dipole \|Δn\|=0, \|Δl\|=1 Rydberg-to-Rydberg couplings. When, as is the essence of the photoexcitation model, the same one n-manifold approximation is made in the model of high-n Rydberg-state photoionization, a number of interesting photoionization effects are obtained. Among them, the most spectacular seems to be the emission of photoelectrons in the ``forbidden'' directions and the suppression of ionization when compared to the Fermi golden rule predictions. However, we show on the basis of an approximate analysis that these photoionization effects can be strongly diminished when additional n manifolds around the selected one are included in the model. Thus, we conclude that the one n-manifold approximation overestimates results when applied to the problem of high-n Rydberg-state photoionization.
Physical Review A
- Pub Date:
- February 2000
- Multiphoton ionization and excitation to highly excited states;
- Strong-field excitation of optical transitions in quantum systems;
- multiphoton processes;
- dynamic Stark shift