Computation of the widths of doubly excited states coupled by external AC or DC fields

The authors have computed the variation of the widths of two doubly excited states of H - , the discrete 2p 23 P and the autoionizing 2s2p 3 P 0 , as a function of the intensity and of the on- and off-resonance frequency of a laser, and of the field strength of a DC field. In the field-free case, the width of the 2s2p 3 P 0 state is due to the Coulomb interaction with the H 1 s in p 3 P 0 channel and is found to be 6.5 meV, in agreement with previous theoretical and experimental investigations. When the fields are turned on, the calculation involves the simultaneous coupling of the two states and 15 open channels and was carried out according to a recently published many-electron many-photon theory.