High-order harmonic generation from arbitrarily oriented diatomic molecules including nuclear motion and field-free alignment

Abstract

We present a theoretical model of high-harmonic generation from diatomic molecules. The theory includes effects of alignment as well as nuclear motion and is used to predict results for ${\mathrm{N}}_{2}$, ${\mathrm{O}}_{2}$, ${\mathrm{H}}_{2}$, and ${\mathrm{D}}_{2}$. The results show that the alignment dependence of high-harmonics is governed by the symmetry of the highest occupied molecular orbital and that the inclusion of the nuclear motion in the theoretical description generally reduces the intensity of the harmonic radiation. We compare our model with experimental results on ${\mathrm{N}}_{2}$ and ${\mathrm{O}}_{2}$, and obtain very good agreement.