We have studied the optically induced NMR effects in anthracene with different optical irradiation spectra and in various samples. Comparison of these results with measured exciton concentrations indicates that the anthracene mobile triplet exciton is not directly responsible for the observed NMR effects. Radiation-induced changes in the anthracene absorption and prompt fluorescence appear to be related to changes in the strength of the induced NMR effects.

• Received 19 April 1968

DOI:https://doi.org/10.1103/PhysRevLett.21.70