Surface Debye temperature of α-quartz (0 0 0 1)

We present thermal attenuation measurements of scattered helium atoms from the surface of α-quartz (0 0 0 1) which are analyzed using Debye theory. The Debye-Waller attenuation of the specular and the first order diffraction peak G11 is measured between 136 K and 384 K. Independent data sets are recorded for beam energies of Ei=66.8 meV and 96.3 meV. The vibration amplitude at room temperature is estimated to be 0.011 nm and agrees well with the simple model of reduced force constants by one-half at the surface. A surface Debye temperature of 360 K is obtained for an effective vibrating mass of 22 a.u.