Influence of temperature on hemicyanine Langmuir-Blodgett multilayer films

Molecular structure and optical nonlinearity in interleaving hemicyanine/ar achidic acid or cadmium arachidate multilayers, and Z-type pure hemicyanine multilayers were investigated as a function of temperature by means of sec ond harmonic generation (SHG) and linear absorption. The SHG intensity show s a maximum at about 45 degreesC in the multilayers. An inflection was obse rved in the temperature dependence of SHG intensity in the interleaving hem icyanine/ arachidic acid and hemicyanine/cadmium arachidate multilayers, an d was attributed to the melting of arachidic acid or cadmium arachidate. Th e absorption spectra show that the molecules in the multilayers formed H-ag gregates which could be dissociated by heating. (C) 2000 Elsevier Science B .V. All rights reserved.