Effect of viscosity and temperature on some photophysical parameters of 9-phenyl-10-methoxy anthracene

9-Phenyl-10-methoxy anthracene (PMA) shows no significant change in the absorption spectrum on going from non-polar to polar solvents, indicating no change in dipole moment of dye molecules upon excitation. The fluorescence quantum yields (Φf) of PMA have been measured in different solvents. It was found that Φf and the lifetime (τf) increases with increasing the viscosity of solvent. It was also found that the fluorescence quantum yields (Φf) increased sharply by lowering the temperature. The quenching rate constants by molecular oxygen were measured using lifetime measurements.