DISSOCIATION DYNAMICS OF FAST IONIZED H2+ BEAMS INCIDENT AT GLANCING ANGLES TO CU(111)

Autor(en): HARDER, R
NESBITT, A
HERRMANN, G
TELLIOGLU, K
RECHTIEN, JH
SNOWDON, KJ
Stichwörter: AG(111); CHARGE-TRANSFER; Chemistry; Chemistry, Physical; CRYSTAL-SURFACE; ELECTRONIC-TRANSITIONS; INDUCED DESORPTION; MOLECULAR-IONS; NEUTRALIZATION; Physics; Physics, Condensed Matter; SIMPLE METALS; SURFACE SCATTERING; VIBRATIONAL-EXCITATION
Erscheinungsdatum: 1994
Herausgeber: ELSEVIER SCIENCE BV
Journal: SURFACE SCIENCE
Volumen: 316
Ausgabe: 1-2
Startseite: 63
Seitenende: 80
Zusammenfassung: 
We have applied the technique of translational spectroscopy to a study of the dissociation dynamics of fast (0.1-0.5upsilon(F) H-2+ beams incident at normal energies from 0.2-8 eV to a Cu(111) surface. Neutralization is very efficient. Mechanical excitation processes directly related to the crystal surface corrugation do not appear to be responsible for dissociation of the molecule. Instead, the spectral features and their dependences on incident beam energy, normal energy and centre-of-mass scattering angle are well reproduced by a classical simulation which assumes that the H-Cu interaction is purely repulsive, and the H-H interaction is either purely repulsive or even attractive. This result is consistent with either charge transfer to the surface modified H-2b3SIGMA(u)+ state on the incident trajectory, or to the H-2X1SIGMA(g)+ state followed by strong coupling of this state to electronically excited states of the H-2/Cu system via the potential surface hopping mechanism described in the accompanying paper [Surf. Sci. 316 (1993) 47], or both. We see no evidence for an orientation dependence of the charge transfer step. It is possible to associate specific features of the measured kinetic energy release distributions as a function of final internuclear axis orientation, angular distributions and translational energy distributions with specific classes of trajectories and specific internuclear separations and molecular axis orientations during scattering. The essential form of the measured distributions is determined by the large difference in the amount of translational energy dissipated in the near surface region by each fragment of the molecule.
ISSN: 00396028
DOI: 10.1016/0039-6028(94)91129-0

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