Use of the oxygen KLL Auger lines in identification of surface chemical states by electron spectroscopy for chemical analysis

X-Ray photoelectron study of the reaction of oxygen with cerium

On the chemical nature of the carbonaceous deposits on iron after CO hydrogenation

Multiply charged molecules

: This paper is divided into two parts. Firstly, a review of desorption methods is presented, with emphasis on the use of temperature programmed desorption (TPD) and electron stimulated desorption (ESD) for understanding the bonding of adsorbed species to surfaces. Secondly, recent studies of the angular distribution of ESD ions from adsorbed layers on W(011) are discussed. The ESD of O(+) ions from oxygen adsorbed on a stepped W(011) surface is shown to be sensitive to the presence of atom steps. (Author)

Desorption Methods as Probes of Kinetics and Bonding at Surfaces.

We have used Auger spectroscopy as a probe of local chemical environment both in the gas and condensed phases using a systematically chosen series of molecules [H2O, CH3OH, (CH3)2O, CH4, C2H4, and C2H2]. For the series of gas phase molecules, H2O, CH3OH, (CH3)2O, and CH4, where oxygen and carbon are, respectively, in similar bonding arrangements, characteristic fingerprint spectra (methanelike for C and waterlike for O) are shown to result. Additional fine structure, which is dependent on the specific molecular environment, appears on the spectra. In contrast, dramatic differences are observed for the series CH4, C2H2, and C2H4 in which major differences in hybridization exist at the carbon site. H2O, CH3OH, and (CH3)2O were studied both in the gas phase (electron excited) and in the condensed phase (x‐ray excited). The O(KVV) (K level–valence–valence transition) and C(KVV) spectra are shown to be similar when comparing the gas–solid results only if the multilayer spectra are properly corrected for electr...

Chemical‐state effects in Auger electron spectroscopy

It has long been suggested that Auger spectroscopy, the most widely used surface analytical technique, should be capable of yielding chemical information in addition to its normal role for surface elemental analysis. However, to date this application has only been minimally developed. The Auger process, in contrast to that of photoelectron spectroscopy, involves a direct coupling between core and valence states and, as a result, yields spectra which are sensitive to the valence electronic structure local to a specific atom (i.e., its local chemical environment). This aspect of Auger spectra was experimentally and theoretically probed through the use of a coherent set of molecules investigated both in the gas and solid phases. The relative peak positions are directly related to the ionization potentials of the various valence orbitals while the peak intensities are a direct measure of the variation of local atomic (as opposed to bonding) charge populations across the valence orbitals. Moreover, in the condensed phase, where intermolecular bonding operates through a specific atom in the molecule (i.e., O in solid H/sub 2/O), the Auger spectra clearly show this local effect.

R. R. Rye

Papers

Chemical‐state effects in Auger electron spectroscopy

Chemical information in Auger spectroscopy