THE STUDY OF NE2-SURFACE SCATTERING( IONS PRODUCED BY ELECTRON PROMOTION IN NE+ ION)

A systematic study of doubly charged Ne2+ ions scattered from Fe (1 1 0), Ni (1 0 0) and Cu3Au (1 0 0) surfaces has been performed using low energy singly charged Ne+ projectiles (less than or equal to 7 keV). Scattered Ne2+ ions have been observed at projectile energies above a threshold. The Ne2+ yields scattered from the corresponding Fe, Ni and Cu atoms on the surfaces have been measured as a function of the prim ary ion energy under various scattering geometries. A charge exchange model is described for the formation and neutralisation of the scatter ed Ne2+ ions. Neutralisation of the Ne+ projectile along the incoming trajectory has also taken into account. A simple expression for the sc attered Ne2+ ion yield is presented, which matches the experimental da ta well. The ionisation probability for Ne+ --> Ne2+ or Ne-0 --> Ne2in the violent collision and the characteristic velocity v(c) '' for N e2+ along the exit trajectory have been extracted by fitting the model to experimental data. For further understanding about the process inv olving Ne2+ ions, the inelastic energy loss associated with the scatte red Ne2+ ions has also been presented and discussed. (C) 1997 Elsevier Science B.V.