SCATTERING OF REACTIVE AND INERT ION-BEAMS FROM SURFACES - ENERGY-LOSS, STRAGGLING AND SKIPPING

We compare and contrast the scattering behaviour of beams of the 'chemically active' species H+ and N+ with that of the 'chemically inert' species He+ and Ar+. The 3-3.5 keV beams were incident at from 1-8-degrees to a Cu(111) surface. The scattered neutral particle energy distributions were recorded at scattering angles in the range 1-9-degrees with a 0.2-degrees angular resolution using a time-of-flight (TOF) technique. We analyse the mean energy loss and straggling as a function of incidence, scattering and azimuthal angles, and beam species. Both quantities behave in a complex manner as a function of these variables. No universal behaviour was found. We report regularly spaced peaks in the scattered Ar atom energy distributions and evidence for such structures in the scattered N atom distributions. We tentatively associate the fine structure in at least the Ar distributions with transient adsorption or skipping motion of a portion of the beam on the surface.