Spectromicroscopy of complex interfaces and real-time reaction studies at ELETTRA

The high performance levels in spatial and time resolutions achieved in photoelectron spectroscopy using third-generation synchrotron sources 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) focused into a submicron spot allowed the elemental and chemical characterization of submicron-sized three-dimensional phases on bimetal/Si interfaces. The composition of the subphases and their evolution during the formation processes were revealed, as was the impact of the surface morphology on the local reactivity of these laterally heterogeneous interfaces. The high photoelectron yield combined with the high energy resolution made the collection of N 1s and O 1s core-level spectra possible every few seconds during NO adsorption on a Rh(110) surface. These spectra were used as a measure of the dissociation and the molecular adsorption rate, and as a fingerprint for the changes in the chemical identity and bonding of the surface species.