The triplet state in fluid media

Abstract Absorption spectra of the triplet states of a variety of organic molecules have been observed in fluid solutions at normal temperatures. Triplet-triplet spectra are given for thirty-two molecules and, for ten of these, absolute extinction coefficients and oscillator strengths have been measured. In most cases several distinct electronic transitions have been found and the energy levels and oscillator strengths of these transitions are compared with the results of molecular orbital calculations for the first five linear polyacenes. Triplet-state lifetimes have been measured for naphthalene and anthracene in a wide range of solvents and the effect of dissolved gases, particularly oxygen, on these lifetimes is described.