This proposal is in the general area of analytical and surface chemistry and in the subfield of surface chemical kinetic studies. The efforts of two investigators, Drs. John Hemminger and Robert McIver, are combined to utilize a new approach previously developed involving laser induced thermal desorption of transient species during a chemical reaction, and their detection by Fourier transform mass spectrometry. The key advantage of this method is the ability to detect multiple species simultaneously. The method will be used to study the kinetics of transformation of hydrocarbon molecules coadsorbed with heteroatom containing molecules as a function of concentration and coverage at well characterized single crystal surfaces. In particular, the studies using the laser induced thermal desorption-Fourier transform mass spectrometry method will focus on three projects. The first involves the study of collective phenomena involving two coadsorbates on platinum ?111! as a function of coverage. The second involves complex tranformations such as dehydrocyclization of simple alkanes and alkenes over catalytically relevent single crystal surfaces. The third project will focus on the effects of bismuth postdosing to block specific surface chemical sites on the adsorbate, thereby examining the influence of such blockage on transformation kinetics of ethylene to ethylidyne on Pt?111!.
