The Adsorption of Cycloparaffins on Ru(001) as Studied by Temperature Programmed Desorption and Electron Stimulated Desorption.
NATIONAL BUREAU OF STANDARDS WASHINGTON DC SURFACE SCIENCE DIV
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The adsorption of C2H6, and the cycloparaffins C3H6, C6H12, and C8H16 on Ru001 at 80 K has been studied using LEED, temperature programmed desorption, and ESDIAD Electron Stimulated Desorption Ion Angular Distributions. An aim of these studies has been to examine the relationship between ESDIAD ion desorption angles and bond angles in weakly adsorbed species having known internal structure. Fractional monolayers of C2H6 and C3H6 both yield ESDIAD patterns due to H ions desorbed in wide cones centered on the surface normal, consistent with adsorption into mobile, disordered layers. In contrast, a fractional monolayer of C6H12 yields a hexagonal H ESDIAD pattern. These results indicate the azimuthal orientation of the C-H bonds and are consistent with a simple model of C6H12 adsorption. In thermal desorption studies, the weakly adsorbed layer in contact with the substrate is easily distinguished from condensed multilayers. Mass analysis of ESD ions reveals that the only ESD ion product is H for hydrocarbon coverages 1 monolayer. For multilayers of adsorbed C6H12 and C8H16, the ESD ion products have a mass distribution similar to the gas phase mass spectrometer cracking pattern. For all these fragments, the ESD cross sections are approx. or 2 x 10 to the -17th power sq cm. Author
- Physical Chemistry