The temperature dependence of the magnitudes and positions of the peaks in LEED intensity–energy plots

Measurements of the temperature dependences of the intensities and energies of LEED peaks in the intensity plots for the specular beam from a (111) copper surface are reported. An analysis is made, for the peak shifts as a function of temperature, in order to attempt to deduce the thermal expansion coefficient for the surface layers normal to the surface. Several additional effects are accounted for but the shifts appear to be dominated by an unknown process and no deductions are drawn concerning the expansion coefficient. The temperature dependence of the intensities of the Bragg peaks in the intensity plots give values for the Debye temperature as a function of primary electron energy. The results indicate that this is not strongly dependent on diffraction condition. From the Debye temperature, the ratio of the mean square vibrational amplitude of the surface atoms perpendicular to the surface to that for the bulk is found to be 1.9 ± 0.1, in agreement with theoretical predictions.