SCATTERED-LIGHT DUE TO EXCITED SURFACE-PLASMON IN ARACHIDIC ACID LB ULTRATHIN FILMS ON SILVER THIN-FILMS

Scattered light due to excited surface plasmon in arachidic acid (C20) Langmuir-Blodgett (LB) ultrathin films on the silver (Ag) thin films was measured to obtain information about surface roughness of the film s. The scattered light intensities were assumed to be described by a l inear superposition of roughness spectra, and the experimental angular distributions were explained by some pairs of the transverse correlat ion length sigma and the surface corrugation depth delta. The angular spectra strongly depended on the roughness parameters, sigma and delta . The roughness parameters for the C20 LB films were decided by fittin g the theoretical angular patterns to the experimental results. The an gular spectra varied with the number of the C20 LB monolayers on the A g films. It is suggested that the surface roughness of the C20 LB film s changed with the number of monolayers. The scattered light method is useful for evaluating surface roughnesses of LB ultrathin films. (C) 1998 Elsevier Science S.A. All rights reserved.