The optical properties of copper phthalocyanine ultrathin films deposited on silver: An ATR study

Ultrathin copper phthalocyanine adsorbate layers have been deposited onto s ilver films, and their optical properties in the visible spectral range hav e been investigated by angle-dependent attenuated total reflection measurem ents in Kretschmann-Raether prism coupler geometry. Down to an adsorbate ma ss coverage of 2 nm. the optical behaviour of the adsorbate is in accordanc e with the bulk optical constants of copper phthalocyanine. For thinner lay ers, the optical behaviour indicates an increase in the average absorption cross section of the copper phthalocyanine molecules at the silver surface. The effect may be explained as resulting from "hot spots" at the silver su rface, originating from surface irregularities.