Multilayer mixed films of cadmium stearate (SC) containing perylene-4-octadecanon (PO) with long chain C17H35 were prepared by the Langmuir-Blodgett technique. By itself, PO was found to form good Langmuir Blodgett films because it was possible to produce high quality multilayers. The molar ratios of PO to SC were varied from 1.5% up to 100%. Using the time-correlated single-photon counting technique and fluorescence spectroscopy, evidence of dimer formation of PO molecules in Langmuir Blodgett films was obtained.