ARTIFACT FORMATION IN SCANNING PHOTOELECTRON EMISSION MICROSCOPY

The fast developing analytical technique, synchrotron radiation scanni ng photoemission spectromicroscopy has opened the opportunity for prob ing surface processes and composition of materials on a submicron spat ial scale. Here we describe some artefact and unforeseen phenomena tha t can occur when a photon flux with high intensity is focused onto a m icrospot. Using as examples selected data obtained recently with the s canning photoemission microscope built at the ultrabright synchrotron source ELETTRA we illustrate the possible effects of surface morpholog y and undesired processes, such as photon-assisted carbon deposition, heat dissipation, charging and photon-induced reduction of the sample. All these events can cause severe changes in the chemical maps and ph otoelectron spectra and provide misleading results. The physical natur e of the artefacts are outlined and discussed, as well as the possibil ities to reduce their influence or to use them for quantification of s ome photon-induced phenomena becoming important in spectromicroscopy e xperiments carried out at the third generation synchrotron sources. (C ) 1998 Elsevier Science B.V. All rights reserved.