TEMPERATURE EFFECTS IN DIRECTIONAL ELASTIC PEAK ELECTRON-SPECTROSCOPYFOR THE CU(011) FACE - OBSERVATION OF THE SURFACE ROUGHENING TRANSITION

Polar profiles of directional elastic peak electron spectroscopy (DEPE S) and directional Auger electron spectroscopy (DAES) were measured fo r the Cu(011) face in the vicinity of particular close-packed directio ns in the sample and for sample temperatures of 400<T<1200 K. For all directions investigated, the In C versus T curve, where C is the contr ast: C = 2(I-max-I-min)/ (I-max + I-min) for a particular maximum in t he polar profile, is composed of three linear parts. The slope of this particular part is different for the different maxima investigated bu t the breaks between the linear parts occur always at the temperatures T-1 approximate to 700 K and T-2 approximate to 1000 K. The former br eak is ascribed to the appearance of anharmonic thermal vibrations whi le the latter one indicates the surface roughening transition. DEPES w as applied for the first time in the investigation of the surface roug hening transition and it was found to be a very convenient and effecti ve method. The surface roughening temperature T-R approximate to 1000 K was found for the Cu(011) face, in an excellent agreement with theor etical predictions.