The blends of a nonlinear optical dye with polycarbonate are described and comparisons are made with solutions of the dye in chloroform. Absorption spectra of blends with up to 1 wt% lead tetracumylphenoxy phthalocyanine showed the dye to be primarily in the monomer form. The monomer absorption spectrum and the measured extinction coefficient replicated those in chloroform solution. As the dye concentration increased to 20 wt %, the monomer intensity decreased and new spectral features characteristic of the dimer appeared. The spectra were resolved into contributions of monomer and dimer, and the concentration effect was analyzed according to the monomer/dimer equilibrium. Much higher monomer concentrations were achieved in polycarbonate blends compared to chloroform solutions. It was concluded that when the blends were quenched from the melt, the equilibrium established at the melt temperature was preserved in the solid state glass. Quenching the blend from different melt temperatures confirmed this interpretation. Extrapolation of the temperature dependent equilibrium constant to 25 degrees C yielded a value close to that reported for chloroform solution at 25 degrees C. (c) 2007 Wiley Periodicals, Inc.