Friction of conduction electrons with adsorbates - Simultaneous changes of DC resistance and broadband IR reflectance of thin Cu(111) films exposed to CO

We present an experimental study of the simultaneous changes induced by CO adsorption in the DC resistivity and broadband IR reflectance of thin Cu (111)-oriented epitaxial films over the spectral range 180-3000 cm(-1). The experiments were carried out at the synchrotron infrared beamline U4IR at the NSLS, Brookhaven National Laboratory. A linear relationship is found between the DC resistivity change and the asymptotic limit of the IR reflectance change, and a quantitative comparison is made with the model of diffuse scattering. of the conduction electrons by the adsorbates. Despite various adsorption states and geometrics for CO on Cu(lll) as a Function of coverage, no departure from a linear dependence was observed. In addition, the integrated intensity of the CO stretch mode at 2072 cm(-1) shows saturation with increasing coverage far before saturation of the resistance and reflectance change. (C) 1999 Elsevier Science B.V. All rights reserved.