Near surface yield enhancement in narrow acceptance 180/sup 0/ elastic scattering for He ions in non-crystalline and poly-crystalline solids. [0. 8 to 1. 6 MeV]
Observations of an unusual near-surface (0 less than or equal to x less than or equal to 700A) yield enhancement in the energy distribution of elastically scattered He ions from amorphous and polycrystalline materials is reported. The integrated excess yield for small (theta/sub 1/2/ = 0.2/sup 0/) versus large (theta/sub 1/2/ = 4.5/sup 0/) acceptance angle at 180/sup 0/ scattering is typically 20% for He energies in the range 0.2 less than or equal to E less than or equal to 2.5 MeV. Maximum peak-to-normal yield ratios as high as 60 to 70% were observed. Materials in which the effect was observed include amorphous germanium, the glassy metal alloy Nb/sub 40/Ni/sub 60/, fine-grained polycrystalline Au, Pt, Mo, and Cu, and also single crystals of Si and Au continuously rotated during data collection to simulate a random lattice. The excess yields are largest for materials of atomic number above Z = 40, and decreases rapidly for elements below this value. The angular width and depth dependences of this effect suggest that it is sensitive to multiple scattering and also imply that the particle, upon scattering, must retrace its inward path within a cone of less than or equal to 0.2/sup 0/ from depths comparable to or less than a few hundred Angstroms. 5 figures.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5636068
- Report Number(s):
- CONF-790843-13(Draft); TRN: 80-003795
- Resource Relation:
- Conference: 8. international conference on atomic collisions in solids, Hamilton, Canada, 13 Aug 1979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
HELIUM IONS
BACKSCATTERING
COPPER
ION COLLISIONS
GERMANIUM
GOLD
MOLYBDENUM
PLATINUM
SILICON
NICKEL BASE ALLOYS
NIOBIUM ALLOYS
AMORPHOUS STATE
ATOMIC NUMBER
ELASTIC SCATTERING
EXPERIMENTAL DATA
GRAPHS
KEV RANGE 100-1000
MEV RANGE 01-10
POLYCRYSTALS
YIELDS
BINARY ALLOY SYSTEMS
ALLOY SYSTEMS
ALLOYS
COLLISIONS
CRYSTALS
DATA
DATA FORMS
ELEMENTS
ENERGY RANGE
INFORMATION
KEV RANGE
METALS
MEV RANGE
NICKEL ALLOYS
NUMERICAL DATA
PLATINUM METALS
REFRACTORY METALS
SCATTERING
SEMIMETALS
TRANSITION ELEMENTS
640301* - Atomic
Molecular & Chemical Physics- Beams & their Reactions