INVESTIGATION OF ELECTROMAGNETIC FIELDS AT A ROUGH Ag SURFACE BY DIFFERENTIAL REFLECTOMETRY OF Cu AND Al ADSORBATES

Abstract

Submonolayer deposits of Copper and Aluminium on rough silver surfaces prepared by quenching silver on substrates cooled to 120 K are studied by differential reflectivity in the 2-4 eV spectral region. For both adsorbates (Cu and Al) similar optical absorptions are observed at ~ 1.8 eV and ~ 3 eV and are unambiguously assigned to surface roughness. It is found that the optical absorption at ~ 1.8 eV has nearly the same spectral position and width than SERS excitation spectra reported by Pockrand (Chem. Phys. Lett. 92 (1982) 514) for Ag surfaces similar to our