Alignment dependent ultrafast electron-nuclear dynamics in high-order harmonic generation

TL;DR

This study explores how molecular alignment affects ultrafast electron-nuclear dynamics during high-order harmonic generation in diatomic molecules, revealing spectral modulations useful for imaging molecular structures.

Contribution

It introduces a non-Born-Oppenheimer approach to model HHG in diatomic molecules at arbitrary alignments, highlighting the role of nuclear motion in spectral features.

Findings

Nuclear motion causes spectral modulation in HHG.

Redshifts decrease with increased molecular alignment.

Spectral features are sensitive to initial vibrational states.

Abstract

We investigated the high-order harmonic generation (HHG) process of diatomic molecular ion $\mathrm{H}_2^+$ in non-Born-Oppenheimer approximations. The corresponding three-dimensional time-dependent Schr\"odinger equation is solved with arbitrary alignment angles. It is found that the nuclear motion can lead to spectral modulation of HHG. Redshifts are unique in molecular HHG which decrease with the increase of alignment angles of the molecules and are sensitive to the initial vibrational states. It can be used to extract the ultrafast electron-nuclear dynamics and image molecular structure.