Reaction Dynamics at Semiconductor Surfaces

Contains report on one research project

Reaction Dynamics at Semiconductor Surfaces

Contains report on one research project

Oxygen Adsorption on Au–Ni(111) Surface Alloys

Molecular O[subscript 2] dissociates upon interaction with a Ni(111) surface, as the spatial and energetic overlap between the Ni 3d electrons and the O[subscript 2] antibonding orbitals is quite favorable. On a Au–Ni(111) surface alloy where the extent of this overlap is greatly reduced, exposure to O[subscript 2] results in adsorption of molecular O[subscript 2] characterized by three peroxo- or superoxo-like vibrational bands centered at 743, 856, and 957 cm[superscript –1] as observed by high resolution electron energy loss spectroscopy. These bands correspond to the stretch vibrational mode of O[subscript 2] at respective adsorption sites of type pseudo-3-fold fcc/hcp, degenerate-pseudo-2-fold fcc/hcp and bridge, and pseudo-3-fold bridge. These unusual chemical environments are brought about by surface alloying, rather than the presence of Au clusters on Ni, and are further stabilized by a dramatic reconstruction of the top two surface layers, as explained with an idealized surface alloy model in conjunction with electronic structure considerations. The ability to adjust the relative populations of the different oxygen cohorts by varying the Au content suggests the utility of surface alloy motifs for engineering applications.United States. Dept. of Energy (DE-FG02-05ER15665)Shell-MITEI Seed Fund Progra

Chemical Reaction Dynamics at Surfaces

Contains reports on four research projects.Joint Services Electronics Program Contract DAAL03-92-C-000

Chemical Reaction Dynamics at Surfaces

Contains reports on four research projects.National Science Foundation (Grant DMR81-19292)National Science Foundation (Grant CHE82-06422)Research CorporationCamille and Henry Dreyfus FoundationMonsant

Chemical Reaction Dynamics at Surfaces

Contains reports on three research projects.Joint Services Electronics Program (Contract DAAL03-86-K-0002)Joint Services Electronics Program (Contract DAAL03-89-C-0001)National Science Foundation (Grant CHE 85-08734)MIT Energy Laboratory - Synthetic Fuels CenterPetroleum Research Fund (Contract 19014-AC5

Energy distribution analysis of the wavepacket simulations of CH4 and CD4 scattering

The isotope effect in the scattering of methane is studied by wavepacket simulations of oriented CH4 and CD4 molecules from a flat surface including all nine internal vibrations. At a translational energy up to 96 kJ/mol we find that the scattering is still predominantly elastic, but less so for CD4. Energy distribution analysis of the kinetic energy per mode and the potential energy surface terms, when the molecule hits the surface, are used in combination with vibrational excitations and the corresponding deformation. They indicate that the orientation with three bonds pointing towards the surface is mostly responsible for the isotope effect in the methane dissociation.Comment: 20 pages LaTeX, 1 figure (eps), to be published in Surf. Sc

Chemical Reaction Dynamics at Surfaces

Contains reports on four research projects.Center for Materials Science and EngineeringCamille and Henry Dreyfus FoundationNational Science Foundation (Grant CHE82-06422)Research CorporationNational Science Foundation (CHE85-08734)Synthetic Fuels Center of the Energy Laboratory at M.I.T.Center for Materials Science and EngineeringMonsant

Chemical Reaction Dynamics at Surfaces

Contains reports on three research projects.Joint Services Electronics Program Contract DAAL03-89-C-0001Joint Services Electronics Program Contract DAAL03-92-C-0001National Science Foundation Grant CHE 90-2062