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

TL;DR

This paper investigates the detailed pathway of dissociative ionization in D$_2$ molecules under intense, short laser pulses, revealing the role of electronic state coupling and intermediate states in the ionization process.

Contribution

It provides a detailed quantum dynamical analysis of the dissociative ionization pathway, highlighting the importance of intermediate electronic states and internuclear distance dynamics.

Findings

Ionization involves coupling between $1s \sigma_g$ and $2p \sigma_u$ states.

Transition to ionization occurs via intermediate states, not directly.

Internuclear distance distribution shifts to larger values during ionization.

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.