The Huygens Principle of Angle-Resolved Photoemission

TL;DR

This paper presents a Huygens principle-based approach to angle-resolved photoemission spectroscopy that simplifies analysis while capturing complex interference effects and final state phenomena.

Contribution

It introduces a Huygens principle framework for ARPES that extends the plane wave approximation to include phase shifts and distortions, enabling efficient analysis of interference effects.

Findings

The method accurately describes photoelectron distributions in various systems.

It captures momentum-dependent interference effects and dichroism.

The approach offers a low-cost alternative to ab initio calculations.

Abstract

Angle-resolved photoemission spectroscopy (ARPES) measures the interference of dipole allowed Coulomb wavelets from the individual orbital emitters that contribute to an electronic band. If Coulomb scattering of the outgoing electron is neglected, this Huygens view of ARPES simplifies to a Fraunhofer diffraction experiment, and the relevant cross-sections to orbital Fouriertransforms. This plane wave approximation (PWA) is surprisingly descriptive of photoelectron distributions, but fails to reproduce kinetic energy dependent final state effects like dichroism. Yet, Huygens principle of ARPES can be easily adapted to allow for distortion and phase shift of the outgoing Coulomb wave. This retains the strong physical intuition and low computational cost of the PWA, but naturally captures momentum dependent interference effects in systems that so far required treatment at the ab initio level, such as linear dichroism in Rashba systems BiAg2 and AgTe.