Photophysical characteristics of 9-cyanoanthracene molecules organised in Langmuir[ndash ]Blodgett films

Abstract

Multilayers of 9-cyanoanthracene (CNA) mixed with stearic acid (SA) have been incorporated in Langmuir–Blodgett (LB) films. The surface pressure–area isotherms in the mixed systems in different mole fractions, form stable floating compressible layers on the water subphase. The low area per molecule at high concentration of CNA in the mixed systems indicates multilayer or aggregate formation of CNA molecules in the film within the SA matrix. Steady-state and time-resolved spectroscopic studies reveal that CNA forms aggregates in LB films at room temperature. Presence of nascent trans- and cis- excimeric sites in these aggregates has been confirmed by the two excimeric emissions observed in the LB film at 77 K. Scanning electron microscopy confirms the presence of such aggregates in the LB films.