Determination of the surface Debye temperature of Mo(112) using valence band photoemission

The interplay between the surface band structure and possible surface reconstructions of Mo(112)

“…We show that the band structure is temperature dependent below 250 K. Above 250 K the photoemission intensities are consistent with the dynamic motions of surface atoms as a function of temperature, as outlined elsewhere [18]. An understanding of the stability molybdenum surfaces, in terms of the electronic structure, may have more general signifi cance beyond the general tendency of Cr, Mo and W to reconstruct [2].…”

“…At higher temperatures, well above the temperature where the decrease in density of states near the Fermi level is observed, photoemission intensities follow the expected temperature dependence of electron-phonon scattering (Debye scattering), as previously noted [18]. (For our purposes we only need to consider the effective (as noted by Waldfried et al [18]), not the true surface Debye temperature.)…”

“…The order of the Mo(112) surface was verifi ed by LEED and the absence of surface contamination by photoemission and the sample was prepared using well-established procedures [18]. The surface of the Mo(112) crystal was cleaned by repeated annealing in oxygen and electron bombardment (fl ashing) and the crystal temperature was monitored with a W-5%Re W-26%Re thermocouple with an accuracy of 5 K. Exposure of the Mo(112) crystal to oxygen was controlled with the use of a standard UHV leak valve.…”

“…(For our purposes we only need to consider the effective (as noted by Waldfried et al [18]), not the true surface Debye temperature.) For temperatures less than 250 K, as summarized in Figure 11, deviations from the expected Debye scattering occur.…”

“…We have plotted the intensity of the surface resonance, in the photoemission spectra at 3.1 to 2.8 eV binding energy, where the surface resonance intensity is most easily abstracted in Figure 11, rather than the states near the Fermi energy where the signal to noise is not as large. This variation in photoemission intensities cannot be modeled by simple dynamic motion variations in temperature [18].…”