Laser-induced electron diffraction: alignment defects and symmetry breaking

ABSTRACT

The fringe pattern that allows geometrical and orbital structure information to be extracted from LIED (laser-induced electron diffraction) spectra of symmetric molecules is shown to reflect a symmetry conservation principle. We show that under a field polarisation 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 factorisation 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.

KEYWORDS:

• LIED
• photoelectron spectra
• intense fields
• alignment
• alignment defects molecular orbitals
• symmetry conservation
• symmetry-adapted linear combination
• symmetry breaking

Acknowledgments

The authors acknowledge the use of the computing cluster GMPCS of the LUMAT federation (FR 2764 CNRS). O. Atabek acknowledges the organising committee of the André D. Bandrauk Honorary Symposium on Molecules and Laser Fields in Orford (QC), Canada, May 2016, for giving him the opportunity of an invited talk partly covering the subject of this article.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

European Union (EU) Seventh Framework Programme [Project ITN - 2010 - 264951, CORINF]; Natural Sciences and Engineering Research Council of Canada [Grant Number RGPIN-2015-05369].