LB薄膜の配向構造と機能
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概要
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In recent years, much attention has been devoted to Langmuir-Blodgett (LB) films consisting of organized molecular assemblies in the form of ultrathin layers. Concomitantly, there has been an in-creased need for establishment of characterization methods of LB film structures. Among the various analytical methods applicable to thin organic films, Fourier transform infrared (FT-IR) spectroscopy provides the most powerful tool for the analysis of constituent groups in molecules. <BR>Recently, we proposed a new method for quantitative evaluation of-the molecular orientation by combining FT-IR reflection-absorption (RA) and transmission techniques, and applied it to the study of LB films of cadmium stearate, azobenzene-containing long-chain fatty acids and their barium salts, and polyion complexes. Here, I outline this method and results obtained for LB films of C<SUB>m</SUB> H <SUB>2m-1</SUB>, -φ-N=N-φ- (CH<SUB>2</SUB>) <SUB>n</SUB>-COOH (m=8 or 12, n=3 or 5) and their barium salts. Furthermore, I discuss about relationship between the molecular orientation evaluated by the above method and pyroelectricity in alternating (noncentrosymmetric) Y-type LB films consisting of a phenylpyrazine-containing long-chain fatty acid and perdeuterated stearic acid as well as of their barium salts. Finally, I describe new FT-IR reflection techniques such as metal overlayer attenuated total reflection (ATR) method for improving the sensitivity of spectral measurements and external reflection method for thin organic films extended on nonmetalic substrates with the absorption coefficients less than unity.