Hole burning and single-molecule spectroscopy of terrylene in incommensurate biphenyl

Techniques of spectral hole burning and single-molecule spectroscopy have been used to study thin films of polycrystalline terrylene-doped biphenyl at temperatures between 1.7 and 2.2 K. A very wide range of probabilities of photoinduced spectral transitions of terrylene molecules are indicated by the strong non-exponentiality of non-photochemical hole burning processes and observation of some extremely stable single-molecule lines. Broad distribution of single-molecule linewidths as well as obvious disagreement between their average value and the corresponding holewidth also demonstrate a large variety of spectral behaviour of terrylene impurity molecules. We attribute these effects to spatial variations of local environment of terrylene molecules in an incommensurate matrix of biphenyl.