Hiroyuki Sasabe

Alkyl Chain Length Effect on Growth Kinetics of n-Alkanethiol Self-Assembled Monolayers on Gold Studied by X-Ray Photoelectron Spectroscopy

Growth kinetics of self-assembled monolayers (SAMs) of n-alkanethiols on gold substrates was studied by X-ray photoelectron spectroscopy (XPS). We compared adsorption kinetics for three alkanethiol homologues: butanethiol (C4SH), dodecanethiol (C12SH), and octadecanethiol (C18SH). Results of quantitative analysis by XPS suggested that the adsorption rate of short alkyl chain thiols is higher than that of long ones on gold substrates at the initial growth stage, in contrast to previous reports. For C4SH SAM formation, we have also confirmed the occurrence of a replacement effect from contamination to SAM on gold, based on our observation of a decrease in the amount of carbon and an increase in the amount of gold where as determined from XPS spectra.

Synthesis and properties of monolithic photorefractive carbazole-derived calix[4]arenes

As a new class of multi-functional compounds, three kinds of calix[4]arene molecules were newly synthesized: calix[4]arenes containing two 3-nitro-N-allyl carbazoles, two N- allyl carbazoles and one of each at the lower rim. These compounds take cone conformation in solution because of the 1,3-di-O-substitution at the lower rim. Those compounds take amorphous state as proved by differential scanning calorimetry and powder X-ray diffraction and they can be made into films without supporting the polymer matrix. Second- harmonic generation signals were observed in the films of the two calix[4]arenes containing nitro groups after electric poling at a temperature above glass transition point. Enhancement of d33 in the calix[4]arene with nitrocarbazole derivatives compared with the calix[4]arene with both carbazole and nitrocarbazole derivatives was observed, which might be attributed partially to some extent to the conformational regulation between the two carbazole chromophores. Using two beam couple experiment, photorefractive effect was observed in the film of the calix[4]arene with both carbazole and nitrocarbazole derivatives doped with 2,4,7-trinitro-9-fluorenone. This is the first report on the photorefractive property of calix[4]arene compound.

Scanning Tunneling Microscopy Investigations on Heteroepitaxially Grown Overlayers of Cu-Phthalocyanine on Au(111) Surfaces

With its ultrahigh resolution, the STM provides an outstanding capability for the structural analysis of the molecular orderings occurring on single crystalline substrates.

Fixation of protein molecules for STM measurement

New deposition technique, ‘‘guest‐host anchoring method’’, has been developed for scanning tunneling microscopy (STM) visualization of biological macromolecules with clear discrimination against artifacts. The electroactive protein (cytochrome c3) molecules were embedded in the liquid crystal matrix, and imaged by STM as a function of applied voltage. Those STM images are encouraging for potential application of this new method to the STM imagings of a wide range of uncoated biological macromolecules.