SPECTROMICROSCOPY OF COMPLEX INTERFACES AND REAL-TIME REACTION STUDIES AT ELETTRA

The high performance levels in spatial and time resolutions achieved i n photoelectron spectroscopy using third-generation synchrotron source s are demonstrated by recent results obtained on heterogeneous Au + Ag /Si(111) interfaces and the interaction of NO with a Rh(110) surface. Scanning photoemission microscopy with more than 10(9) photons s(-1) f ocused into a submicron spot allowed the elemental and chemical charac terization of submicron-sized three-dimensional phases on bimetal/Si i nterfaces. The composition of the subphases and their evolution during the formation processes were revealed, as was the impact of the surfa ce morphology on the local reactivity of these laterally heterogeneous interfaces. The high photoelectron yield combined with the high energ y resolution made the collection of N 1s and O 1s core-level spectra p ossible every few seconds during NO adsorption on a Rh(110) surface. T hese spectra were used as a measure of the dissociation and the molecu lar adsorption rate, and as a fingerprint for the changes in the chemi cal identity and bonding of the surface species.