Singletmdash;triplet exciton absorption spectra have been measured in naphthalene and pyrene single crystals at room temperature by observing the dependence of the ``antihyphen;Stokes'' emission intensity resulting from mutual annihilation of triplet pairs on the wavelength of exciting light. The origin of the naphthalene spectrum is at 21 170 cmminus;1, and the most prominent intervals in the vibrational structure are 490 and 1360 cmminus;1. The origin of the pyrene spectrum is at 16 850 cmminus;1, and the vibrational structure for the lowest triplet state in this crystal includes the intervals 410, 1210, 1380, and 1590 cmminus;1.
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