Electron stimulated desorption of H/sup +/, O/sup +/, and OH/sup +/ from H/sub 2/O adsorbed on niobium

Journal Article · Wed Jul 01 04:00:00 EDT 1987 · J. Vac. Sci. Technol., A; (United States)

DOI:https://doi.org/10.1116/1.574673· OSTI ID:6512453

Rey, S; Roman, E; de Segovia, J L

H/sub 2/O layers adsorbed on polycrystalline niobium at a temperature of about 150 K have been studied by means of the electron stimulated desorption (ESD). The O/sup +/, H/sup +/, and OH/sup +/ surface ions are recorded by maintaining the surface under continuous electron bombardment and corresponding to the dissociated species O, H, and OH, respectively. When the surface is exposed to H/sub 2/O with no e/sup -/ bombardment the ESD ions are H/sup +/ and OH/sup +/, with very low, if any, O/sup +/ yield. The origin of the ion species has been determined on the basis of their thresholds and ion energy distribution. The ionization of the Nb 4p core level at about 30 eV is responsible for the ejection of H/sup +/ from the Nb--H or Nb--O--H bonds, and the O/sup +/ from the Nb--O bond. A Nb surface atom ''multiadsorbate'' bonds model of the dissociated products, H and OH, is proposed to explain the origin of the various ESD ion species. The influence of the e/sup -/ bombardment on surface species and the thermal desorption spectra of the H/sub 2/O layer are also presented. The first one shows that the e/sup -/ bombardment increases significantly the surface species yielding O/sup +/ ESD ions and a model for its formation is proposed. The thermal desorption spectrum of mass 16 (O) at relatively low temperatures has its origin from ESD of neutral O atoms.

• Research Organization: Laboratorio de Fisica de Superficies, Instituto de Ciencia de Materiales, C.S.I.C. Serrano 144, 28006-Madrid, Spain
• OSTI ID: 6512453
• Journal Information: J. Vac. Sci. Technol., A; (United States), Journal Name: J. Vac. Sci. Technol., A; (United States) Vol. 5:4; ISSN JVTAD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ADSORPTION
CATALYSIS
CATIONS
CHARGED PARTICLES
CHEMICAL REACTIONS
COLLISIONS
DESORPTION
DISSOCIATION
ELECTRON COLLISIONS
ELEMENTS
HYDROGEN COMPOUNDS
HYDROGEN IONS
HYDROGEN IONS 1 PLUS
HYDROXYL RADICALS
ION COLLISIONS
IONS
METALS
NIOBIUM
OXIDATION
OXYGEN COMPOUNDS
OXYGEN IONS
RADICALS
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
TRANSITION ELEMENTS
WATER