Dibromonaphthalene Crystals coherent, one-dimensional Triplet Excitons

Dibromonaphthalene Crystals coherent, one-dimensional Triplet Excitons 

The dibromonaphthalene (DBN) crystal differs in its crystal structure (Fig. 2.14) considerably from the structure of the polyacene crystals (Fig. 2.10) the unit cell of DBN contains eight molecules, which belong to two non-equivalent sublattices I and II. The excitation energies of the triplet excitons in the sublattices I and II differ by 50 cm. At low temperatures, therefore, only the excitons in one of the sublattices are excited. Each sublattice consists of linear stacks of DBN molecules along the c axis of the crystal. The exciton transport along this stacking axis is also predominant the triplet excitons in in DBN crystals are quasi-one-dimensional excitons. 

From the analysis of the ESR line shape and width using the model of motional narrowing, one obtains the following results for the dynamics of the quasi-one-dimensional triplet excitons in DBN  

CO = 27t -35 Ghz. (a) The intensities /+, Iq and / of the three individual Zeeman components of the 0,0 transition of the 7 So phosphorescence at 20 192 cm were measured as functions of the applied magnetic field Bq for constant microwave power, (b) The ESR spectrum measured with the usual microwave detection. After [20]. 

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