Influence of the Au(111) reconstruction on the light emission induced by a scanning tunneling microscope

Abstract

STM-induced light emission on reconstructed Au(111) is investigated under UHV at room temperature. Light emitted from the tunnel junction is recorded simultaneously with topography using a Au tip. For positive sample biases, a contrasted periodic pattern on the photon map anticorrelated with the reconstruction features of the topography is observed. For negative sample biases, the contrast on the photon map is strongly reduced. In order to understand the link between reconstruction and photon emission, variations in tunnel current and in photon emission are also recorded as a function of tip-sample distance. These measurements show that the contrast on the photon map does not result from variations in the coupling of inelastically tunneling electrons with the radiative tip-induced plasmon mode. Instead, the photon contrast is correlated with the relative variations upon scanning of the local density of final states for elastically and for inelastically tunneling electrons.