Evidence for the stopping of slow ions by elicitations of optical phonons in insulators

The energy loss of Net ions with keV energies scattered under grazing incid ence from a LiF(001) surface is studied with a time-of-flight technique. Si nce charge exchange in font of the wide-band-gap insulator is widely suppre ssed, the energy loss of slow ions moving in front of the solid can be inve stigated under specific interaction conditions. From the theoretical analys is of data we find evidence for an energy loss mechanism based on the excit ations of optical phonons in the insulator.