Excimer Delayed Fluorescence of Compressed Naphthalene Crystals

The compression of naphthalene crystals (to 30 kbar) at 77°K irreversibly, defects in the lattice. These defects capture singlet and triplet excitons, leading exclusively to excimer and delayer excimer fluorescence. Triplet trap depths of $\text{∼600}\mathrm{cm}\text{−1}$ at 1 atm and $\text{∼700}\mathrm{cm}\text{−1}$ at 30 kbar are estimated from the temperature dependence of the delayed excimer fluorescence. A wide distribution of singlet trap depths and excimer conformations is indicated by the pressure modifications of the excimer fluorescence band.