Electronically stimulated sputtering and luminescence from solid argon

Journal Article · Mon Feb 01 04:00:00 EST 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.37.1455· OSTI ID:5708346

Reimann, C T; Brown, W L; Johnson, R E

Electronic excitation of condensed-gas solids by MeV light ions results both in luminescence and in kinetic ejection of atoms and molecules from the surface of the solid. This work reveals that ejection of Ar atoms from electronically excited solid argon films arises from two nonradiative repulsive dissociation steps in the deexcitation decay sequence which contains the major radiative transition. A hole-diffusion model with nonradiative quenching at the metal substate on which the films are grown accounts for the dependence of the sputtering and luminescence on film thickness and gives an estimate of 230 A for the hole-diffusion length. The hole-diffusion model also explains the nearly linear dependence of the sputtering and luminescence yields on electronic stopping cross section for high-velocity incident ions. Intentionally added O/sub 2/ and N/sub 2/ impurities reduce the hole-diffusion length. These reductions provide values for effective reaction volumes, k/sub +/tau/sub +/, of 7 x 10/sup -21/ cm/sup 3/ for O/sub 2/ and 3 x 10/sup -21/ cm/sup 3/ for N/sub 2/, where k/sub +/ is the interaction rate constant of the holes with the impurity and tau/sub +/ is the lifetime of holes in pure films. The O/sub 2/ and N/sub 2/ impurities also quench nonmobile luminescent excimers, Ar/sub 2//sup */, over large distances: 21 A for O/sub 2/ and 11 A for N/sub 2/. The magnitude of the sputtering yield characterizes the vacuum interface as primarily hole reflecting, but with a surface-hole-trapping rate about 6 times that of the bulk. Surface O/sub 2/ impurity greatly enhances surface trapping of free holes. Sputtering of Ar/sub 2//sup */ dimers is evident from the observation of 11.3-eV luminescence in the region in front of the argon films. The dimers are emitted with approx.0.8 eV of kinetic energy.

• Research Organization: School of Engineering and Applied Science, University of Virginia, Charlottesville, Virginia 22901
• OSTI ID: 5708346
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 37:4; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

656003* -- Condensed Matter Physics-- Interactions between Beams & Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ARGON
BEAMS
CHARGED PARTICLES
DIFFUSION LENGTH
DIMENSIONS
ELEMENTS
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EXCITATION
FILMS
FLUIDS
GASES
HELIUM IONS
HYDROGEN IONS
ION BEAMS
IONS
KINETICS
LENGTH
LUMINESCENCE
MEV RANGE
NONMETALS
RARE GASES
SOLIDS
SPUTTERING