Laser-Induced Electron Diffraction: Alignment Defects and Symmetry Breaking

TL;DR

This paper analyzes how symmetry and alignment defects affect laser-induced electron diffraction (LIED) spectra, demonstrating the robustness of certain spectral features against deviations from perfect molecular alignment.

Contribution

It introduces a symmetry-based formalism to understand the effects of alignment defects on LIED spectra, highlighting the stability of perpendicular alignment configurations.

Findings

LIED spectra are robust against certain alignment deviations.

Symmetry conservation principles explain spectral features.

Perpendicular alignment shows strong spectral stability.

Abstract

The fringe pattern that allows geometrical and orbital structure information to be extracted from LIED spectra of symmetric molecules is shown to reflect a symmetry conservation principle. We show that under a field polarization which preserves certain symmetry elements of the molecule, the symmetry character of the initial wave function is conserved during its time-evolution. We present a symmetry analysis of a deviation from a perfect alignment by decomposing the field into a major, symmetry-determining part, and a minor, symmetry breaking, part. This decomposition leads to a corresponding factorization of the time-evolution operator. The formalism is applied to the analysis of the robustness of LIED readings and inversions with respect to deviations from a perfect perpendicular and parallel alignment of a symmetric ABA triatomic molecule. The results indicate a particularly strong stability of the type of LIED spectra associated with the perpendicular alignment situation.