High resolution photoemission study on SnO2 gas sensors

Pd-, Pt-doped and undoped SnO2 gas sensors were studied by synchrotron radi ation photoelectron spectroscopy (SRPES) and laboratory source UPS (ultravi olet photoelectron spectroscopy). Valence band spectra were recorded for ph oton energies of 60-120 eV (SRPES) and for 40.81 eV (UPS). The spectra were analyzed by factor analysis and generation of difference spectra. A compar ison of the samples shows that the doping material of these sensors is not introducing additional states to the surface electronic structure within th e limit of detection. This leads to the conclusion that the surfaces of the grains are not enriched with the metal additives. (C) 2001 Elsevier Scienc e B.V. All rights reserved.