Single and double photoemission and generalizations

TL;DR

This paper presents a unified diagrammatic framework for analyzing single and double electron photoemission processes, connecting Green's function methods with scattering theory for relevant physical scenarios.

Contribution

It introduces a comprehensive diagrammatic approach for single and double photoemission, linking nonequilibrium Green's functions with scattering theory for the first time.

Findings

Unified diagrammatic treatment of photoemission processes

Correspondence established between Green's functions and scattering theory

Framework applicable to higher-order electron coincidence processes

Abstract

A unified diagrammatic treatment single and double electron photoemission currents is presented. The irreducible lesser density-density response function is the starting point of these derivations. Diagrams for higher order processes in which several electrons are observed in coincidence can likewise be obtained. For physically relevant situations in which the photoemission cross-section can be written as the Fermi Golden rule, the diagrams from the nonequilibrium Green's function approach can be put direct correspondence with that of the scattering theory.