Angular distributions from two-photon detachment of H- near ionization threshold: Laser-frequency and -intensity effects

Abstract

We have performed a nonperturbative Floquet study of the angular distributions of the emitted electrons in the two-photon detachment of H- driven by strong infrared laser fields. The external field parameters are chosen to correspond to the recent experiment by R. Reichle, H. Helm, and I. Yu. Kiyan, Phys. Rev. Lett. 87, 243001 (2001). We discuss the laser-frequency and -intensity effects on the shape of the angular distribution in the vicinity of the ionization threshold. We show that the angular distribution pattern can be interpreted in terms of the interference of the s and d partial waves in the final state and the Wigner threshold law.