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The absorption spectra of 9-anthroic acid (9-anthracenecarboxylic acid) in ethanol have been measured as a function of solute concentration. It was revealed that 9-anthroic acid forms a hydrogen-bonded dimer. The equilibrium constant for dimer formation was determined to be 6.6×104 mol−1 1 in ethanol at 298 K. The fluorescence spectra of 9-anthroic acid have been investigated as a function of concentration and temperature in various solvents. An excimer mechanism was proposed for a broad fluorescence of 9-anthroic acid; the hydrogen-bonded dimer is excited and then associates with an unexcited hydrogen-bonded dimer to form an excited tetramer from which the broad fluorescence occurs.

COONTER-J / (imm) / ~.~ CdSe SnO z ~lM.m ~O.I~m

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Electrochemical properties of WO3 films prepared by vacuum evaporation and stored in high humidity atmosphere have been studied in organic electrolytes. Structures of the film have been analyzed by electron diffraction analysis and x‐rays. It has been found that the evaporated amorphous WO3 film is crystallized to form WO3·H2O crystal and furthermore H2WO4·H2O from surface layer to bulk layer in high humidity air. Hydrated WO3·xfalse(H2Ofalse) crystal layer may act as a high resistant layer on the electrochemical reaction, so that the hydrated layer, remarkably, loses the electrochromic activity.

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Electrochemical properties of evaporated amorphous WO3 films on conductive glass substrates have been studied in propylene carbonate electrolytes, and the degradation of the electrochromic activity of the WO3 film on storage in the electrolyte and the prevention of the degradation of the film have been investigated by cyclic voltammetry. The WO3 films have also been analyzed by XPS, SIMS, and FT-IR spectra. We have confirmed that the thermodynamic degradation is accelerated by H20 and LiC104 in the electrolyte. It is proposed that: first, H20 contributes to the change of WO~ into W(OH)~; second, Li ~ exchanges with the H § of W(OH)~; and then these reactions result in the formation of Li.~WO~; and, consequently, in the negative shift of the cathodic reaction potential of the film. We have also confirmed that the degradation is prevented by addition of an acid, such as I4~PO4 or acrylic acid, to the LiC104 PC electrolyte and by using LiBF4 as a supporting electrolyte in place of LiC104.Since the important paper of Deb (1), there have been numerous studies (2-8) of the electrochromic (EC) properties of WO3 films. Electrochromic displays (ECD) using WO3 thin films will be classified into three groups: WO3/liquid electrolyte, WO3/solid electrolyte, and WOJdielectric layer systems. The WO~/liquid electrolyte systems have been studied frequently, and EC properties of this system, such as respQnse and memory, are superior to other systems. Faughnan (5) reported a WOJglycerol-H~SO4 liquid electrolyte system which had a fast response, but it had problems of the dissolution of the WO3 film on the shelf and the corrosion of transparent electrode during color/bleach cycling (9). In order to overcome these problems, nonaqueous organic solvents have been investigated as the electrolyte solvent. Randin (9) reported that evaporated WO~ film dissolved about 10% under storage for 90 days at 50~ in acetonitrile and dimethylformamide, etc., but the film dissolution was negligibly small in ~-butyrolactone and propylene carbonate (PC) under the same conditions. Furthermore, Li salts have been used in the supporting electrolytes as a cation source in place of protons because the mobility of Li is the next highest. Problems of the dissolution and the corrosion have been solved by using LiC104 PC electrolyte.However, even in the WO3/LiC104 PC system, the problem of degradation of electrochromic activity on storage for long time and/or cyclic drive still remained.Schlotter et al. (10) reported that the degradation with cycling was caused by ion exchange between Li and protons of W(OHL. Morita et al. (11) also reported that the origin of the mechanism dominating the degradation was essentially the accumulation of Li in the film with SIMS data and Auger analysis.In this paper, the mechanism of degradation of the WO3 film on storage in Li salts-PC electrolytes and preventive methods for the degradation will be described. ExperimentalPreparation of W03 films.--W03 films were deposited by an electron beam evaporation method. WO3 targets (99.99...

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