Structural dynamics of 2,3-dimethylnaphthalene crystals revealed by fluorescence of single terrylene molecules

Single terrylene molecules were detected for the first time in 2,3-dimethylnaphthalene crystals. Experiments provided information about the structural dynamics of the crystal over a wide temperature range. Blinking of the fluorescence intensity of terrylene molecules, between 5 and 150 K, was related to dynamics of the methyl groups of the host molecules surrounding the probe. Photo-bleaching of single terrylenes, monitored over the whole temperature range, at temperatures above 220 K was attributed to thermally activated reorientation of the host molecules, already discovered by nuclear magnetic resonance. Photo-bleaching time was too short to detect terrylene molecules at temperatures above 260 K.