A STUDY OF THE STRUCTURE OF ADSORBATES BY ANGLE-RESOLVED SECONDARY ION MASS SPECTROMETRY (BENZENE, PYRIDINE, SILVER)

The ejection of substrate particles by energetic particle bombardment onto surfaces has been demonstrated to be useful in many scientific areas including catalysis, corrosion, and gas adsorption on surfaces. Some progress has been made in gaining a fundamental understanding of the interaction of these energetic particles with surfaces using classical dynamics calculations. These calculations may then be compared with measurements of the angular and energy distributions of secondary ions. It has been found that the angular distributions of secondary ions are very sensitive to the structure of surfaces.;This thesis applies angle-resolved secondary ion mass spectrometry (SIMS) to the study of the momentum dissipation process of the primary ion, especially for organic molecules on surfaces. The experiments conducted will help elucidate the surface chemistry resulting from gas adsorption on metals and help determine the structure of adsorbates on metal surfaces. A key result is that the molecular orientation of organic molecules on surfaces influences the molecular ejection yield and the polar angle distribution of molecular ions in agreement with classical dynamics calculations. In addition, we can use the angular and energy distributions of secondary ions to better understand the mechanisms of molecular ejection, fragmentation, and cluster formation of organic molecules sputtered from surfaces. It is also possible to examine the details of the structure of surface layers. For chlorine adsorbed on Ag{110}, for example, a change in the height of the chlorine adatoms is observed at low coverage where the chlorine adatoms do not exhibit any long-range lateral order. Modification of the Ag{110} surface by Cs atoms and their effect on oxygen adsorption are studied.;In general, we show that the combination of angle- and energy-resolved SIMS experiments with the insights gained from classical dynamics calculations is a useful and unique approach to the study of adsorbate structure on surfaces and to understanding the underlying physical processes of particle ejection due to energetic particle bombardment.