ATTENUATED TOTAL-REFLECTION PROPERTIES AND STRUCTURES IN SQUARYLIUM LB FILMS

The attenuated total reflection (ATR) properties, as a function of the incident angle of the laser beam, were investigated for squarylium (S Q) Langmuir-Blodgett (LB) films on thin Ag layers. Photosensitive SQ d yes exhibit strong absorption in the visible. The ATR curves are stron gly dependent on the number of LB monolayers; the resonant angles at t he dips increase with increasing number of monolayers. The complex die lectric constants of the LB films (uniaxial anisotropic dielectrics) w ere determined by fitting the theoretical ATR curves to the experiment al curves. The ATR properties suggest that the tilt angles of the long axes of the chromophores in the SQ molecules are about 10 degrees fro m the LB film plane for two layers and about 30 degrees for more than four layers, Since H aggregation of SQ molecules in LB films is genera ted on annealing and the absorption spectra change, the ATR properties were also investigated for annealed SQ LB films. The properties are o f interest for optical applications.