ENERGY-LOSS OF LIGHT-IONS SCATTERED OFF AL(110) SINGLE-CRYSTAL SURFACES AT LOW-ENERGY

We present energy loss data taken after grazing incidence scattering o f H+, H-0, He2+, He+, and He-0 off an Al(110) surface, The data is eva luated by means of a procedure that allows to extract surface electron density parameters. The obtained density parameters will be compared to those obtained from a potassium target. The advantage of using Al a nd K is that both can be described by a jellium model. In order to ext ract the electron density parameters we employ a method based on a des cription of the interaction via the force of friction. We find that th e experimental data cannot be fitted using calculated bulk friction co efficients, Thus we suggest that the friction of light ions is differe nt at the surface and in the bulk.