Chemical information from ion scattering spectrometry

Ion scattering spectroscopy (ISS) is a well-established surface analysis technique yielding semiquantitative elemental composition with submonolayer sensitivity. Poor sensitivity to low mass elements, limited resolution of high mass elements, and the lack of an ability to easily determine molecular species on the surface have limited the usefulness of ISS in surface analysis. Recent observations have shown oscillations in the scattered ion yield with incident energy for certain elements related to the neutralization probability of the ion-atom pair. Presented are oscillatory ion scattering spectroscopy (OISS) curves for a series of closely related lead compounds with the incident energy of the helium probe ion ranging from 500 to 4000 eV. These data show OISS to be very sensitive to the chemical environment of the target atom and so can be used to positively identify the chemical species in cases where normal ISS cannot. The use of OISS as a surface probe yielding chemical composition information greatly expands the usefulness of ISS while at the same time solving some of its inherent limitations. For those types of analyses requiring molecular information about the surface monolayer, such as catalysis and chemisorption studies, OISS may become one of the most powerful probes into this complex region. 15 references, 4 figures, 1 table