Crystal perylene-doped

An example of exciplex formation in the solid state may be afforded by perylene doped crystals of pyrene which emit a green structureless fluorescence in addition to the blue and orange-red excimer bands of pyrene and perylene, respectively. Hochstrasser112 has shown that the energy of the emitting species is consistent with that of a charge transfer complex of pyrene and perylene molecules in a bimolecular unit of the pyrene lattice. 

F%. 35a-d. Anomalous temperature broadening with the bend in the pe a octaethylporphin in polystyrene [99[t h doped silicate glass [1003- Time scale of the hole-burning > 100 s (dots) and < S s(circ(es cNddop BlGaZYTZ heavy metal fluoride glass (crosses) and Nddc >ed ED-2 silicate glass (circles) [101] d perylene doped n-octane crystal [102, 103]... 

Figure 5 Superior photoconductivity, normalized to an absorption of 1 cm" perylene and NI doped liquid crystal versus R6G doped sample.

Along the path from isolated, oriented molecules to excitons in non-doped crystals, we next take up the triplet states of oriented dimers, which we called mini-excitons in Sect. 6.4. Mini-triplet-excitons are excitations of triplet states which are spatially distributed over exactly two molecules, for example the two A and B molecules in the unit cell of Fig. 7.11, and they are localised there. In principle, mini-excitons can also be localised on a pair of molecules with the same orientation in crystals with a dimeric structure, e.g. in the a-perylene crystal (Fig. 2.12). We will however restrict ourselves in this section to the treatment of A - B mini-excitons. 

EPR spectroscopy has been used very extensively in investigations of hemoproteins and heme model systems. In all studies on high- and low-spin hemoproteins, no hf interaction with N, or (enriched) Fe was resolved in frozen solutions or in single crystals. The first EPR observation of ligand hf structure from heme pyrrole nitrogens in the model system ferriprotoporphyrin(IX) ester doped into perylene single crystals was reported by Scholes The hfe tensors were found to be essentially isotropic wi a, ol = 8.68 MHz, which corresponds to a spin density fj = 2.7% in the nitrogen 2s-orbital. 

---