Excitation induced frequency shifts of single molecules

We have developed an experimental scheme to observe frequency shifts of single molecule absorption lines induced by a controlled manipulation in the surroundings in the solid state at low temperatures. In a mixture of terrylene and triphenylene in the matrix n-octane many single terrylene molecules are observed in parallel with a fluorescence microscope while triphenylene molecules are excited to their long-living triplet state. Frequency shifts are induced upon excitation and relaxation of triphenylene, resulting in increased spectral dynamics of terrylene molecules during the relaxation period.