A HIGH-PRECISION ATR STUDY OF SURFACE-PLASMON MEDIATED REFLECTANCE INNOBLE-METAL FILMS

An ATR reflectometer was constructed using a twin goniometer system an d lock-in detection technique. The angular resolution was +/-0.015 deg rees, determined by the beam divergence of the He-Ne and YAG laser lig ht sources, while the error in reflectivity was less than +/-2%. The a ngular distribution of the ATR reflection and backward resonance light emission was measured in evaporated silver and gold films of 30-90 nm thickness with both wavelengths (0.6382 and 1.064 mu m). Exact roughn ess spectrums were determined by a fitting procedure using the Kroger- Kretschmann formulae. A relatively sharp thickness dependence was foun d in the components of the dielectric constant at both wavelengths.