THE TEMPERATURE-DEPENDENCE OF THE INVERSE PHOTOEMISSION FROM COPPER SURFACES

The temperature dependence of the intensity of inverse photoemission transitions into bulk and surface states has been studied on Cu(100), (110) and (111) surfaces. On Cu(100) and (111) the temperature dependence can be fitted very well with a Debye-Waller law where the mean square displacements of the surface atoms increase linearly with temperature. On Cu(110) we find an enhancement of the mean square displacements above 400 K in agreement with other scattering experiments. Through the comparison of the same bulk transition on different surfaces we find a strong influence of surface vibrations on the intensities of bulk transitions. The one-step model of photoemission and the result of phonon calculations for surface vibrations have been combined to give a theoretical description of the measured temperature dependencies. © 1990 Pergamon Press plc.