PM-IRRAS SPECTROSCOPY OF 9CB LIQUID-CRYST AL THIN-FILMS DEPOSITED ON A METALLIC SUBSTRATE .2. MOLECULAR-ORIENTATION FROM QUANTITATIVE-ANALYSIS

We present a quantitative analysis of Polarization Modulated InfraRed Reflexion-Absorption Spectra (PM-IRRAS) of 9CB liquid crystal ultra-th in films deposited on a gold substrate. Orientation and conformation o f the 9CB molecules relative to the metallic substrate are deduced by comparing the PM-IRRAS spectra intensities and those measured on the a bsorbance spectrum of bulk sample. From spectra of the crystalline pha se recorded at room temperature, we found the principal axis of the 9C B molecules tilted 35-degrees from the substrate normal and some evide nces for a twist of the alkyl chain around this principal axis.