Pathway of D$^{+}$ in Sequential Double Ionization of D$_2$ in an Intense Laser Pulse

Abstract

We show the details of the pathway for dissociative ionization process of ground electronic state of aligned D$^{+}_{2}$ due to first ionization of D$_2$ in short ($\thicksim$100 fs) and intense ($4.0\times10^{14}$ W cm$^{-2}$) 480 nm laser pulses. The initial vibrational state of D$^{+}_{2}$ comes from the vertical transformation of the ground state of D$_{2}$. The initial wavepacket in the ground electronic state of D$_{2}^{+}$ is outgoing through dissociation-ionization channel accompanied by a strong coupling between $1s \sigma_{g}$ and $2p \sigma_{u}$ electronic states. We show explicitly that the transition from the coupling states $1s \sigma_{g}$ and $2p \sigma_{u}$ to the ionization state is not a direct transition but takes place through other intermediate states with some dissociation energy that results in the internuclear distribution of the ionization to move considerably to larger internuclear distances.