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Self-organization in reactions at surfaces
A365 Surface Science 287/288 (1993) 1-11 North-Holland
Self-organization in reactions at surfaces G. Ertl Fritz-Haber-lnstitut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-IO00 Berlin 33, Germany Received i September 1992; accepted for publication 3 October 1992 The techniques of surface science provide detailed insights into the microscopic processes underlying catalytic reactions which form, on the other hand, the basis for appropriate modelling of the macroscopic kinetics. For constant external conditions, the rate of a catalytic reaction is, however, not necessarily stationary, but may become oscillatory or even chaotic. These effects are associated with non-uniform distribution of the adsorbed species over the surface on a mesoscopic scale, and their theoretical description is based on the concepts of nonlinear dynamics. Experimental verification of these phenomena of spatio-temporal self-organization is demonstrated with the catalytic CO oxidation on a Pt(ll0) surface as example.
Surface Science 287/288 (1993) 12-15 North-Holland
Low energy H~- molecular ion scattering from the Si(100) surface Hiroyuki Hirayama Microelectronics Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba 305, Japan Received 17 July 1992; accepted for publication 24 November 1992 Low energy (1200 eV) H~- molecular ion scattering (LEMIS) from the Si(100)(2 x 1) surface was studied. Energy spectra of scattered positive ions were measured as functions of incidence and exit angles. In the scattering spectrum, the only detected positive ion species was H +, meaning that the H~- was dissociatively scattered. Dissociation by an impulsive force and dissociation with neutralization are discussed as possible mechanisms of the H~ dissociative scattering. The scattering angle dependence of the surface peak energy supports the former mechanism.
Surface Science 287/288 (1993) 16-20 North-Holland
Role of projectile-motion-induced electronic transitions in the dissociation of fast H 2 at a Cu(111) surface R. Harder, K. Tellioglu, A. Nesbitt, G. Herrmann, A. Golichowski and K.J. Snowdon Fachbereich Physik, Universitiit Osnabriick, Postfach 4469, D-4500 Osnabriick, Germany Received 26 August 1992; accepted for publication 24 November 1992 We report measurements of the final molecular axis orientation, released kinetic energy and incident beam translational energy dependence of dissociative scattering of 500-6000 eV Hz and H~- from Cu(lll) under glancing angles of incidence (normal energies 0.7-4 eV). We find some evidence that the scattering dynamics of those molecules initially in the ground X 1E~- state may be influenced by the topography of the continuum manifold of PES correlating with the adiabatic ground state. However, we suggest that electronic transitions from the ground state manifold to a dissociative upper state manifold are ultimately responsible for the dissociative scattering events we detect.
Self-organization in reactions at surfaces G. Ertl Fritz-Haber-lnstitut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-IO00 Berlin 33, Germany Received i September 1992; accepted for publication 3 October 1992 The techniques of surface science provide detailed insights into the microscopic processes underlying catalytic reactions which form, on the other hand, the basis for appropriate modelling of the macroscopic kinetics. For constant external conditions, the rate of a catalytic reaction is, however, not necessarily stationary, but may become oscillatory or even chaotic. These effects are associated with non-uniform distribution of the adsorbed species over the surface on a mesoscopic scale, and their theoretical description is based on the concepts of nonlinear dynamics. Experimental verification of these phenomena of spatio-temporal self-organization is demonstrated with the catalytic CO oxidation on a Pt(ll0) surface as example.
Surface Science 287/288 (1993) 12-15 North-Holland
Low energy H~- molecular ion scattering from the Si(100) surface Hiroyuki Hirayama Microelectronics Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba 305, Japan Received 17 July 1992; accepted for publication 24 November 1992 Low energy (1200 eV) H~- molecular ion scattering (LEMIS) from the Si(100)(2 x 1) surface was studied. Energy spectra of scattered positive ions were measured as functions of incidence and exit angles. In the scattering spectrum, the only detected positive ion species was H +, meaning that the H~- was dissociatively scattered. Dissociation by an impulsive force and dissociation with neutralization are discussed as possible mechanisms of the H~ dissociative scattering. The scattering angle dependence of the surface peak energy supports the former mechanism.
Surface Science 287/288 (1993) 16-20 North-Holland
Role of projectile-motion-induced electronic transitions in the dissociation of fast H 2 at a Cu(111) surface R. Harder, K. Tellioglu, A. Nesbitt, G. Herrmann, A. Golichowski and K.J. Snowdon Fachbereich Physik, Universitiit Osnabriick, Postfach 4469, D-4500 Osnabriick, Germany Received 26 August 1992; accepted for publication 24 November 1992 We report measurements of the final molecular axis orientation, released kinetic energy and incident beam translational energy dependence of dissociative scattering of 500-6000 eV Hz and H~- from Cu(lll) under glancing angles of incidence (normal energies 0.7-4 eV). We find some evidence that the scattering dynamics of those molecules initially in the ground X 1E~- state may be influenced by the topography of the continuum manifold of PES correlating with the adiabatic ground state. However, we suggest that electronic transitions from the ground state manifold to a dissociative upper state manifold are ultimately responsible for the dissociative scattering events we detect.