Influence of magnetic quantum number m and spin-angular symmetry on sequential double detachment in strong laser fields

We model sequential double detachment of Ag⁻, C⁻, I⁻, and Al⁻ irradiated by 1064  nm light by using a strong-field model and compare the theoretical double-detachment yields with experimental ones. The symmetry of the Al⁻ and C⁻ ground states ensures that the outermost electrons have different magnetic quantum numbers m. The difference in detachment rate for electrons with different m values leads to a 50% higher saturation intensity than expected from application of the strong-field model with ionization rates for m=0 electrons only. For I⁻, emission of two m=0 electrons requires that the I⁺ ion is left in an excited state, and this leads to an increase of 20% in the saturation intensity. Good agreement is obtained with experiment for Ag⁻, C⁻, and I⁻, but a large discrepancy is observed for Al⁻. The calculations thus indicate that rearrangement of electrons over the available m values may not occur for double detachment at low intensities. Finally, we explain why C⁻ and Al⁻ are well suited for further investigations on the effect of the distribution over m values on sequential double detachment.

©2006 The American Physical Society