Charge state effects in atom-surface scattering

J.N. DeFazio, T.M. Stephen, B.L. Peko


Experimental results of atom-surface scattering are presented for variable
energy (25-200 eV) collisions of hydrogen with a polycrystalline copper surface.
Negative ion measurements are made for proton and hydrogen-atom beams impacting
the surface. Energy and angular distributions of the resulting H- ions are
analyzed for an 18 degree angle of incidence. Charge state effects become
apparent in the H ion energy spectra at incident energies less than ~70 eV.
Measurements show that H- ions resulting from incident hydrogen atoms are
approximately 3 eV less energetic than those from protons with the same kinetic
energy. Energy losses can be accounted for by the inclusion of charge state
dependent thresholds in a linear function of incident energy.

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Nuclear Instruments & Methods in Physics Research, Section B, 201(3), 453-459, 
2003.