Photo-stability of single terrylene molecules in 2,3-dimethylnaphthalene crystals

Fluorescence excitation spectra and fluorescence intensity traces of single terrylene molecules in 2,3-dimethylnaphthalene crystals were studied at 5 K and also at temperatures between 200 and 290 K. Terrylene molecules were found to be relatively photo-stable in crystals obtained by cosublimation of both components under an argon atmosphere whereas these molecules were more easily photo-bleached in crystals obtained under a helium atmosphere. It is propose that the diverse behaviour in both groups of crystals is due to different penetration by oxygen and bleaching of terrylene molecules by photo-oxidation. The fully saturated fluorescence detection rates for the (0, 0) and vibronic transitions were studied.