Abstract: Greater surface sensitivity of ion neutralization spectroscopy with respect to uv photoemission spectroscopy

Abstract

We have demonstrated the unique surface sensitivity of ion neutralization spectroscopy (INS) using a series of Si(111) surfaces, which had been subjected to a common cleaning procedure but different subsequent heat treatments. The surfaces produced each showed a sharp 7×7 LEED pattern and the measured initial‐state transition densities by INS were closely similar. In contrast, the electron spectra by uv photoemission spectroscopy (UPS) for these surfaces showed remarkable differences with respect to each other.The INS evidence is taken to mean that for each such surface the outermost surface layer is cleaner than would be concluded from the UPS spectra. Since the UPS spectra include a large component from the selvedge or near‐surface bulk, we propose that the impurities which cause the differences in the spectra reside largely in the selvedge. Thus UPS is shown to be less sensitive than INS to the outermost surface layer which must be probed in the study of chemisorption.Longer heatings of a particular sa...