Inelastic processes in ion/surface collisions: Direct recoil ion fractions as a function of kinetic energy

Journal Article · Mon Sep 15 04:00:00 EDT 1986 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.450932· OSTI ID:5086409

Rabalais, J W; Chen, J

Time-of-flight (TOF) spectra of the scattered and recoiled particles resulting from 1--10 keV Ar/sup +/ ions impingent on surfaces of MgO, Mg(OH)/sub 2/, graphite, Si, and SiO/sub 2/ have been obtained. Measurements of directly recoiled (DR) neutrals plus ions and neutrals only are used to calculate positive and negative ion fractions Y-italic/sub +,-/ from DR events. These positive and negative ion yields observed for DR of H, C, O, and Si have distinctly different behavior as a function of ion kinetic energy. The Y-italic/sub +/ values exhibit a ''threshold-type'' behavior with a steep rise followed by a slowly rising or plateau region at higher energy. The Y-italic/sub -/ values exhibit a maximum in the low energy region followed by a decreasing yield as energy increases. The Y-italic/sub -//Y-italic/sub +/ ratio for C and O is very sensitive to the amount of hydrogen present, with the Y-italic/sub +/ yields dropping as hydrogen concentration increases. The recently developed model for electronic transitions in keV ion/surface collisions which considers Auger and resonant transitions along the ion trajectory and electron promotions in the quasidiatomic molecule of the close atomic encounter is extended to include DR events. Analytical expressions for Y-italic/sub +,-/ are derived for the case of surface atoms in positive, neutral, and negative bonding environments. These model expressions are fitted to the experimental data, allowing determination of the probabilities of ionization in the close atomic encounter and of electron capture along the outgoing trajectory.

• Research Organization: Department of Chemistry, University of Houston, University Park, Houston, Texas 77004
• OSTI ID: 5086409
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 85:6; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640301* -- Atomic
Molecular & Chemical Physics-- Beams & their Reactions
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALKALINE EARTH METAL COMPOUNDS
ARGON IONS
BEAMS
CARBON
CHALCOGENIDES
CHARGED PARTICLES
COLLISIONS
ELEMENTAL MINERALS
ELEMENTS
ENERGY
ENERGY RANGE
GRAPHITE
HYDROGEN COMPOUNDS
HYDROXIDES
INELASTIC SCATTERING
ION BEAMS
ION COLLISIONS
IONS
KEV RANGE
KEV RANGE 01-10
KINETIC ENERGY
MAGNESIUM COMPOUNDS
MAGNESIUM HYDROXIDES
MAGNESIUM OXIDES
MINERALS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
RECOILS
SCATTERING
SEMIMETALS
SILICON
SILICON COMPOUNDS
SILICON OXIDES
SURFACES
TIME-OF-FLIGHT METHOD