Structure and reactions of carbon and hydrogen on Ru(0001): A scanning tunneling microscopy study

The interaction between carbon and hydrogen atoms on a Ru(0001) surface was studied using scanning tunneling microscopy (STM), Density Functional Theory (DFT) and STM image calculations. Formation of CH species by reaction between adsorbed H and C was observed to occur readily at 100 K. When the coverage of H increased new complexes of the form CH+nH (n = 1, 2 and 3) were observed. These complexes, never observed before, might be precursors for further hydrogenation reactions. DFT analysis reveals that a considerable energy barrier exists for the CH+H {yields} CH{sub 2} reaction

Surface composition of some selected Group VIII/gold and Group VIII/tin alloys

We have determined the surface composition of three different solid solutions (5 at. % Ni-Au, 4 at. % Pd-Au and 14 at. % Pt-Au) and two stoichiometric compounds (Ni3Sn and Pt3Sn), all of them selected because of their significance in current catalytic work on group VIII/"inert metal" alloys. Low-energy ion scattering (LEIS), Auger spectroscopy (AES) and selective CO chemisorption applied to Ft3Sn and Ni3Sn yield consistent results. Surface compositions work out at PtO.7Sn and NiO. 2Sn. LEIS applied to 4 at. % Pd-Au and 5 at. % Ni-Au yields surface compositions of 0.8 at. % Pd and 1.6 at. % Ni respectively. AES and CO chemisorption applied to 14 at. % Pt-Au yield surface compositions between 5 and 10 at. % Pt. The results are compared with contemporary theories on surface segregation