Classification of the symmetry of photoelectron dichroism broken by light

TL;DR

This paper explores how polarized light influences photoelectron dichroism patterns in angle-resolved photoemission spectroscopy, revealing how symmetry is broken and classified based on light configuration and sample properties.

Contribution

It provides a group-theoretical classification of dichroism patterns considering various light polarization and incidence conditions on symmetric crystal samples.

Findings

Dichroism patterns depend on light polarization and incidence angle.

Symmetry breaking occurs when the light's direction is imprinted in the pattern.

Classification of patterns based on polarization type and sample orientation.

Abstract

We investigate how the direction of polarized light can affect the dichroism pattern seen in angle-resolved photoemission spectroscopy. To this end, we prepared a sample composed of highly-oriented Bi(111) micro-crystals that macroscopically has infinite rotational and mirror symmetry of the point group $\rm{C}_{\infty\rm{v}}$ and examined whether the dichroism pattern retains the $\rm{C}_{\infty\rm{v}}$ symmetry under the stationary configuration of the light and sample. The direction of the light was imprinted in the pattern. Thereby, we apply group theory and classify the pattern with the configuration of light taken into account. We complete the classification by discussing the cases when the out-of-plane component of the polarization can be neglected, when the incidence angle is either 0$^{\circ}$ or 90$^{\circ}$, when the polarization is either elliptic or linear, and also when the sample is a crystal.