The optical and structural properties for 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) films deposited on Au-coated substrates at the various growth temperatures by the organic molecular beam deposition (OMBD) method have been studied. The planar PTCDA molecules were oriented almost parallel to the substrate surface in the films deposited at the growth temperature of -160° C. Orientational disorder of the molecular planes occurred especially in the films grown at higher substrate temperatures. These films had basically large anisotropy of refractive indices which were evaluated by the prism attenuated total-reflection (ATR) method. The anisotropy of indices decreased for the film grown at the substrate temperature of 100° C. The optical anisotropy has been understood in terms of the molecular orientation.

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An ultrathin α-Sexithienyl (6T) film prepared by an organic molecular beam deposition method on a silver (Ag) film was studied by polarized near edge X-ray absorption fine structure (NEXAFS) spectroscopy using synchrotron radiation and IR-reflection absorption spectroscopy. The carbon K-edge NEXAFS spectrum of 6T was similar to those reported for poly-(3-methylthienylene) and thiophene. Polarized NEXAFS spectra of 6T exhibit strong angular dependence of 1 s→π* resonance intensity, showing that 6T molecules in the film deposited on the Ag film at room temperature had a highly oriented structure. To obtain quantitative information about molecular orientation, this dependence is analyzed by a comparison with theoretical calculation, indicating that the molecular axis is inclined by about 71° to the substrate surface. This angle is almost the same as that reported for 6T film on quartz.

Thermal decomposition of spin-coated films of partly protected polyvinylphenol with the t-butoxycalbonyl ( tBOC-PVP) group has been investigated by monitoring the intensity of the carbonyl stretching peak of the tBOC group by using temperature-variable time-resolved infrared spectroscopy (TR/IR). The temperature programming method has been used for determining the activation energy ( Ea) of the thermal decomposition. We compared the thermal decomposition behavior of tBOC-PVP films with that of the powders and the behavior of a 22% protected tBOC-PVP film with that of a 66% protected tBOC-PVP film. It was found that the Ea of the 22% protected tBOC-PVP film is distinctively higher than the others including the result given from thermogravimetric analysis (TG). In addition, the Ea of the 22% protected tBOC-PVP film increased up to 50 kcal/mol with the decrease of the remaining tBOC group, while the others were constant at 30 kcal/mol. Diglyme, which was used as the solvent in the 22% protected tBOC-PVP film, was residual after the temperature increased above 80 °C, and the reaction velocity of the tBOC group increased in accordance with the generation of the OH group. These results suggest that the OH group, which accelerates the thermal decomposition of tBOC-PVP, is hindered by the residual solvent in the case of the 22% protected tBOC-PVP films.

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