Triplet extinction coefficients of some organic compounds

The triplet extinction coefficients εT of acridine, anthracene, benzanthracene, dibenzanthracene, chrysene, pyrene, and pyrene caroxaldehyde were measured at the visible spectral region at maximum triplet-triplet absorption. We used McClure’s method together with cw lasers as excitation sources to obtain the εT values. Because these triplet extinction coefficients were measured with improved accuracy, we suggest that these compounds be used as standards. We wanted to compare the accuracy of our values with the ones suggested as tentative standards. Further, we tested the validity of McClure’s method on anthracene by increasing the cw laser excitation intensities (power) Iex and recording triplet optical densities ODT. Under the experimental conditions we used, about 100 mW of cw laser power appears to be the upper limit.