Determination of the surface Debye temperature using quasi-triple collisions in low energy ion scattering

Energy spectra of heavy low energy noble gas ions, specularly reflected from a monocrystalline surface into small scattering angles, show the existence of a quasi-triple collision peak. The occurrence of this QT peak results from scattering from 'three atom pit' structures, present at the surface due to thermal vibrations of the target atoms. The temperature behaviour of this peak provides the possibility to estimate the magnitude of the atomic thermal displacements. This possibility is, to a great extent, independent of uncertainties introduced by a lack of knowledge about charge exchange effects and the actual interaction potential. In this investigation the surface Debye temperature of a copper (100) surface is obtained by comparing experimental and calculational results of 10 keV Kr+ ions scattered along different low index directions at the surface. The temperature dependences of the QT and the QD peak in experimental energy distributions of ions, reflected along these azimuthal target directions, agree remarkably with the calculations using the just obtained Debye temperature. The calculated energy distributions exhibit qualitatively well the main characteristics of the experimental ones. (Auth.)