Electron pair emission from a W(001) surface: photon versus electron excitation

Abstract

The electron pair emission from a W(001) surface was studied using a coincidencetime-of-flight spectrometer. The aim of this study was to compare the pair emission uponelectron impact and upon photon absorption. The energy distributions are markedlydifferent for these two experiments. From this we conclude that the photon-stimulated pairemission carries a significant contribution from a double photoemission process, while theprocess of first creating a photoelectron, which in a subsequent collision leads to pairemission, is of less importance.