PHOTODETACHMENT OF H- WITH EXCITATION TO H(N = 2)

We have applied a recently proposed L2 method to evaluate total and partial photodetachment cross sections of H- up to the N = 3 threshold. The method was specially designed to evaluate continuum states when interchannel coupling is very strong, so that the H ion is an ideal system to test its validity. The calculated cross sections exhibit two Feshbach resonances below N = 2, the well-known shape resonance just above the threshold, and five Feshbach resonances converging to N = 3. The structure of these resonances is analyzed in detail, as well as the behavior of the partial cross sections in these regions. We also provide a complete set of Fano and Starace parameters that are useful to interpret the total and partial photodetachment spectra in the resonance regions. Finally, our results are compared with the available experimental data as well as with other theoretical calculations.