Optical detection of magnetic resonance on triplet states in organic crystals

The variety of experiments combining the means of optical spectroscopy with those of electronspin-resonance is demonstrated on the 1:1 CT-crystal anthracene/tetrachlorophtalic anhydride using different excitations (Ssub(O) → S1-band, Ssub(O) → S1-traps and Ssub(O) → T1-band) as well as different emissions (phosphorescence, fluorescence and delayed fluorescence). The experiments revealed the properties of the triplet states of various traps, one of these exhibiting excitonic character. In β-9,10-dichloro-anthracene one-dimensional excitons are found via the DF-ODMR whose frequency is influenced by thermally activated interstack scattering. (orig.)