OPTICAL STUDIES OF SINGLE TERRYLENE MOLECULES IN POLYETHYLENE

Fluorescence excitation techniques have been used to study the optical spectroscopy and dynamics of single impurity molecules of terrylene in a poly(ethylene) matrix at 1.5 K. We observe a variety of spectral diffusion effects, including spontaneous resonance frequency changes on the 10-100 MHz scale which lead to apparent fluctuations in the absorption line width and shape, discontinuous jumps in the resonance frequency of 100-2000 MHz on a time scale longer than 2.5 s, and long-lived light-induced changes in resonance frequency of more than a few GHz (single-molecule spectral hole-burning). We also observe for some molecules the unusual effect that the spectral diffusion rate and the frequency range increase for higher probing light intensity. For completeness, we also show the vibrationally resolved dispersed fluorescence spectrum in the ensemble-averaged (large N) limit, since such spectra have not been reported previously to our knowledge.