Evaluation of Arachidic Acid Langmuir-Blodgett Ultrathin Films on Silver Thin Films from Scattered Light Using Surface Plasmon Polariton Excited at the Interfaces

Yusuke AOKI  Keizo KATO  Kazunari SHINBO  Futao KANEKO  Takashi WAKAMATSU  

IEICE TRANSACTIONS on Electronics   Vol.E81-C   No.7   pp.1098-1105
Publication Date: 1998/07/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Organic Materials for Optics and Electronics)
scattered light,  surface roughness,  surface plasmon polariton,  LB ultrathin film,  arachidic acid,  

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Attenuated total reflection (ATR) properties and scattered light properties were measured for Ag thin films and arachidic acid (C20) Langmuir-Blodgett (LB) ultrathin films on the Ag thin films to obtain the information about their complex dielectric constants and surface roughness utilizing an excited surface plasmon polariton. The complex dielectric constants for the Ag thin films and the C20 LB films were obtained by fitting the calculated ATR curves to the experimental ones. The surface roughnesses of these films were estimated by the angular distribution of the scattered light assuming the Gaussian function as an autocorrelation function and a linear superposition of roughness spectra. The angular spectra strongly depended on the roughness parameters: the transverse correlation length σ and the surface corrugation depth δ. The experimental angular distributions were explained by some pairs of σ and δ. It was suggested that the surface roughness of the C20 LB films changed with the number of monolayers since the angular spectra varied with the number of the C20 LB monolayers on the Ag films. It is thought that the measurement of the scattered light is useful to evaluate surface roughnesses of LB ultrathin films.