Spectral Diffusion of Single Dibenzoterrylene Molecules in 2,3-Dimethylanthracene

We study single dibenzoterrylene molecules embedded in the dipolar disordered crystal 2,3-dimethylanthracene at 1.25 K. Broad linewidths (about 1 GHz, similar to 30 times broader than in the anthracene crystal), high saturation excitation intensities (similar to 1000 times larger than in anthracene), as well as strong spectral diffusions are observed. Additionally, spectral jumping is studied by varying the excitation intensity and the temperature. We propose that the spectral diffusion and dynamic disorder in this system arise from the combination of a static disorder with slight reorientations of the methyl groups of the host molecules.