Structure and ATR properties of spiropyran LB ultrathin films

The attenuated total reflection (ATR) properties and the structures were investigated for Langmuir-Blodgett (LB) ultrathin films of the photochromic dye spiropyran (SP) on Ag and Al coated glasses. The ATR properties strongly depended upon the number of the monolayers of the LB films on the substrates. The theoretical ATR curves were calculated assuming the dielectric constants, and they agreed with the experimental results. The thicknesses were deduced from curve fitting. It is considered that the SP LB films on the Ag films were probably deposited partly in piles, and that the deposition of the photomerocyanine (PMC) form was stabler than that of the SP forms. The changes of the ATR properties caused by UV irradiation and heat treatments were also observed.