MULTIPHOTON DETACHMENT OF H- IN INTENSE ELECTROMAGNETIC-FIELDS

Multiphoton detachment of hydrogen negative ions (H-) is investigated using the non-perturbative Floquet close-coupling theory. Quantitative agreement between the theory and the experiment is obtained within the single-active-electron ansatz and including the effect of core polarization on the process. The well known threshold law of Wigner is confirmed for the multiphoton detachment process in H- and the experimentally observed range of its applicability is shown to be governed by the polarization potential, The effect of channel-opening and its dependence on the intensity of the field are determined. The total rates of detachment of H-, for the fundamental frequency (omega = 1.17 eV) of the Nd laser are presented in the strong coupling domain of intensities; the results show that die 'rate' parameter tends to be comparable to the field frequency for quiver radius alpha0 > 4.5 au, indicating a possible upper limit for the validity of the widely used adiabatic Floquet ansatz, in this system.