The change in morphology of merocyanine-Cd arachidate mixed Langmuir-Blodgett (LB) films induced by hydrothermal treatment (HTT) has been studied using a polarized light photomicroscope and an X-ray diffractometer. By applying HTT of 100% humidity at 70 C for 60 min, the as-deposited J-band with an in-plane anisotropy is reorganized to an isotropic phase with a sharp peak, and the image, initially anisotropic in brightness, becomes isotropic and filled with round superstructures of 0.1 mm or larger in diameter with an average thickness of presumably less than three monolayers. The change in the X-ray diffraction pattern indicates that the Y-type LB lamellar structure remains intact with an enhanced degree of order of the Cdion alignment.

Effects of hydrothermal treatments (HTI) have been investigated on the merocyanine (MS) -Cd arachidate mixed Langmuir-Biodgett (LB) films. The as-deposited J-band is reorganized by HIT under the IOOo/o-humidity condition in the range 3o-90"C, forming a new phase with spectra sharper than those before H1T. The spectra after HIT can be deconvoluted into Bands I and 11, Gaussian-type centered at 5I5 run and 555 ru:n. respectively, and Band m, the remainder identifiable with the J-band with its peak at 59()-600 nm. The relative fraction of oscillator strength of Band 11 is insensitive to both time tH and temperature TH of HIT. The Band-ill and Band-1 fractions are approximated by exponential saturation and decay functions of tH when TIFCOnst, and by sigmoid and inverse-sigmoid functions of TH when tiFCOnst, respectively. These suggest that the reorganization process is described as a first-order reaction between Band-1 and Band-ill components.

Change in morphology of merocyanine -Cd aracbidate mixed Langmuir-Biodgett (LB) films has been studied before and after the bydrothennal treatments (HTT) of 100% humidity at temperatures ranging from 30'C to 90'C using a polarized light pbotomicroscope. By applying IITT, the J-band with an in-plane anisotropy in the as-deposited LB films is reorganized into an isotropic phase characterized with a narrowing of the peak Correspondingly, the microscopic image, initially anisotropic and featureless under polarized light, changes to be isotropic and filled with round-shaped domains as large as O.I mm or more in diameter. Observation of four types of LB samples with different monolayer stacks indicates that each domain is confmed to one single monolayer.

Hydrothermal and dry-heat treatments (HTT and DHT, respectively) in the morocyanine-containing LB films are studied in relation to the "mild" heat treatment, which leads to two different consequences in the spectral change. Close resemblance is found between the HTT -type and the HTT spectra associated with a sharp J-band peak, and also between DHT -type spectra and the DHT ones with a broad band. It is suggested that the underlying processes of the HTT -type and the DHT -type are essentially identical with those of the HTT and the DHT, respectively. The seasonoodependent occurrence of the both types after the "mild" HT suggests that the humid and cool weather leads to the high yield of the HTT -type spectra. The water remaining on the sample is presumably assumed to act as a humidifier to supply the sufficient amount of water for inducing the HTT -type spectral changes.