Resonant two photon dissociation dynamics of HD+ in intense infrared laser field

Abstract

The intensity dependent line shapes of resonant two photon dissociation process in HD+ from the 1sσg (v=6, J=0) are obtained at three different intensities (1.53×1010, 1.53×1012, and 6.12×1012 W/cm2 ) in the wavelength range 16 000–17 200 Å using the resolvent operator formalism. The discrete state v=11, J=1 (1sσg) is the intermediate resonant state. The position of the resonance on the wavelength scale depends strongly on intensity. It is shown that for sufficiently strong fields the earlier semiperturbative theory formulated in analogy with Fano’s theory of atomic autoionization breaks down near resonance due to saturation of the strongly coupled resonant transition. Also, when the dissociative transitions to both the electronic states 1sσg and 2pσu are considered simultaneously, the line shape is altered from that obtained by the superposition of the line shapes of these two transitions separately. The conditions under which a unique time independent transition rate is ill defined are discussed. For such situations the time dependent transition probabilities can be obtained from the effective Fano asymmetry parameters, and line shifts and widths of the ground and resonant states. The limiting transition rates for such cases for short and long pulse times are also shown.