Paper SS-ThP3
Experimental Aspects of Measuring Dissociative Sticking Coefficients of Hydrocarbons on Solid Surfaces with Independently Variable Gas and Surface Temperatures

Thursday, October 23, 2008, 6:00 pm, Room Hall D

The thermal activation of alkanes on transition metals can be studied by a technique of effusive dosing of gases onto the metal surfaces where both gas and surface temperatures are independently variable. Dissociative sticking coefficients, S(T_g, T_s), are measured by monitoring the deposited amount of surface carbon. This relatively simple method allows measurement of dissociative reaction rates of alkanes or other hydrocarbons with about 9 orders of magnitude dynamic range, however, a careful implementation is required to assure good accuracy and relevance. In particular, effects not related to the direct well-defined gas beam or to the surface under study have to be either eliminated or separated which brings several experimental challenges. Ultimately, such S(T_g, T_s) experiments can be used to define reaction rates and transition states for activated dissociative chemisorption reactions that are otherwise difficult to study under ultrahigh vacuum, surface science conditions.