Low-energy ion scattering and direct recoil spectrometry as a probe of ion/gas surface interactions

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5572798

Chen, J N

Scattered ion fractions and vacuum ultraviolet (VUV) photon emission resulting from 1 x 10 keV Ne/sup +/ and Ar/sup +/ ions impinging on magnesium and yttrium surfaces and the corresponding oxidized and hydroxylated surfaces have been measured. A model is developed for electronic transitions in keV ion/surface collisions which considers Auger and resonant transitions along the ion trajectory and electron promotion in the close encounter. Direct recoil ion yields resulting from 1 x 10 keV Ar/sup +/ ions impingement on surfaces of MgO, Mg(OH)/sub 2/, graphite, Si and SiO/sub 2/ have been measured. The positive ion yields exhibit a threshold-type behavior with a steep rise followed by a slowly rising or plateau region at higher energy. The negative ion yields exhibit a maximum in the low energy region followed by a decreasing yield as energy increases. TOF spectra of the scattered and recoiled particles resulting from 1-10 keV He/sup +/, Ne/sup +/, Ar/sup +/, Kr/sup +/, and Xe/sup +/ ions impingement on surfaces of LiF thin films have been obtained. A qualitative model is used to interpret positive and negative ion fractions (Y/sub +1-/) of DR atoms from surfaces with differing chemical environments. These ion yields are sensitive to the chemical environment of the DR atoms in the surface. The direct recoil technique is used to monitor surface kinetics in order to provide direct time-resolved compositions of surface constituents. Applications to decomposition of hexaflurobenzene have found that carbon is deposited on the surface while fluorine is evolved. A mechanism is proposed involving migration of surface fluorine as the rate limiting step.

• Research Organization: Houston Univ., TX (USA)
• OSTI ID: 5572798
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102* -- Chemical & Spectral Procedures
640304 -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ALKALINE EARTH METAL COMPOUNDS
ARGON COMPOUNDS
CATIONS
CHALCOGENIDES
CHARGED PARTICLES
COLLISIONS
ELEMENTS
HYDROGEN COMPOUNDS
HYDROXIDES
ION COLLISIONS
ION-MOLECULE COLLISIONS
IONS
MAGNESIUM COMPOUNDS
MAGNESIUM HYDROXIDES
MAGNESIUM OXIDES
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
METALS
MINERALS
MOLECULE COLLISIONS
NEON COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
RARE GAS COMPOUNDS
SEMIMETALS
SILICA
SILICON
SILICON COMPOUNDS
SILICON OXIDES
SPECTROMETERS
TIME-OF-FLIGHT SPECTROMETERS
TRANSITION ELEMENTS
YTTRIUM