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Negative giant surface potential was realized in a vacuum-evaporated film of tris(7-propyl-8-hydroxyquinolinolato) aluminum(III) [Al(7-Prq) 3 ]. Electroabsorption response of the film presented an inverted polarity to that of tris(8-hydroxyquinolinolato) aluminum (Alq 3 ), suggesting opposite noncentrosymmetry of molecular orientation. Asymmetric dice model with molecular geometric effect has been proposed, and propyl substitution at 7 position of the ligands was indicated to affects the molecular posture on the surface to invert the polarity of noncentrosymmetry. Our results opened a new possibility of controlling molecular orientation in a film for device applications.

To examine the origin of spontaneous noncentrosymmetric molecular dipole orientation of an evaporated film of tris(8-hydroxyquinolinolato) aluminum (Alq3), overlayer deposition of Alq3 on the backside of a peeled Alq3 film was investigated. Although the surface potential (SP) of the backside of the Alq3 film was negative, the SP showed a positive shift by overlayer deposition of Alq3. This means that the spontaneous dipole orientation of Alq3 molecules in the overlayer is opposite to that in the underlayer. A molecular geometric effect due to a bulky molecular shape is proposed as the origin of the noncentrosymmetry.

Long-term measurement of noncentrosymmetric molecular orientation of vacuum-evaporated tris(8-hydroxyquinolinato) aluminum (III) (Alq3) thin film was performed by means of first-order electroabsorption (EA) spectroscopy. This molecular orientation is responsible for the giant surface potential of Alq3 film, and it might be utilized to nonlinear optical devices. Although the EA response presented reduction, the relaxation time constant was on the order of year. Possible mechanisms for the reduction are discussed.

We report an instrument with the combination of solution jet beam deposition method and ultraviolet photoelectron spectroscopy (UPS). The solution jet beam method is a novel technique to fabricate organic thin films in vacuum, where solution of the organic material is sprayed in vacuum. This method can be applied to organic materials which cannot be vacuum evaporated due to thermal decomposition, e.g., ionic organic solids such as cyanine dyes. The present instrument combines this method with UPS, which is a powerful method for investigating the electronic structure of solids. Using this instrument, the UPS spectra of cyanine dye films deposited by the solution jet beam method were measured without exposure to air. The observed spectra were clearer than those of spin-coated films exposed to air., 5pages

A single dose of synthetic cholecystokinin octapeptide (CCK8, 5 micrograms/kg) in a depot carrier was injected subcutaneously into rats 2 and 14 h before the removal of the pancreas and the preparation of isolated pancreatic acini. CCK8 treatment induced no significant change in body weight or total amount of pancreatic DNA, but pancreatic weight, total pancreatic protein and amylase, and the concentration of amylase and total protein relative to DNA were significantly decreased. In acini prepared from CCK8-pretreated rats, responsiveness to maximal and supramaximal concentrations of CCK8 was significantly increased, irrespective of whether the amount of amylase released was expressed relative to DNA or calculated as a percentage of the acinar content. The dose-response curves for CCK8 were similarly shaped in both CCK8-pretreated and control rats but shifted threefold toward higher concentrations of CCK8 2 or 14 h after CCK8 treatment. Specific 125I-CCK binding was significantly increased only for high-affinity binding sites. Although these observations suggest that alterations in pancreatic amylase release could be due to changes at the cholecystokinin receptor, the secretory responsiveness to maximal and supramaximal concentrations of carbachol was also increased without any change in the sensitivity. Moreover, in contrast to the cholecystokinin receptor, there was no change in the number of muscarinic receptors or in their affinity for either agonists or antagonists measured with [3H]quinuclidinyl benzilate.(ABSTRACT TRUNCATED AT 250 WORDS)