ABOVE-THRESHOLD IONIZATION OF NEGATIVE HYDROGEN

We present detailed calculations for two-and three-photon above-thresh old ionization of the negative hydrogen. in addition to calculated val ues for partial wave amplitudes and phase shirts pertaining to recent experimental results [Xin Miao Zhao et al., Phys. Rev, Lett. 78. 1656 (1997)], we also address the question of the asymmetry of photoelectro n angular distributions in ionization under elliptically polarized rad iation, which has been studied experimentally in other negative ions [ C. Blondel and C. Delsart, Laser Phys. 3, 3 (1993); Nucl, Instrum, Met hods Phys. Res, B 79, 156 (1993); F. Dulieu, C. Blondel, and C. Delsar t, J. Phys. B 28, 3861 (1995)].