Fluorescence and absorbance of polystyrene in dilute and semidilute solutions

The fluorescence and absorbance of polystyrene in solution have been measured over a wide range for several molecular weights and solvents. The absorbance at wavelengths below 280 for these molecular weights and solvents is found to be insensitive to the transition between dilute and solutions. Self-absorption of the fluorescence results in a much reduced observed monomer emission high concentration. When this is corrected, the ratio of excimer to monomer fluorescence intensity, I_E/I_M, essentially constant at low concentrations and at most increases only very slowly and smoothly at higher . No significant molecular weight or solvent effects on the concentration dependence of I_E/I_M manifested for these molecular weights and solvents over the concentration range studied. Contrary to reports, fluorescence spectroscopy reveals no abrupt transition between dilute and semidilute solutions.