Single molecule and Shpolskii spectroscopy of terrylene in a series of N-alkanes

We present a study of terrylene in a series of n-alkane matrices with increasing chain length, namely dodecane, tetradecane and hexadecane. Shpolskii absorption spectra provide the macroscopic characterization of the samples, such as site multiplicity, inhomogeneous line widths and positions. Based on this characterization the distributions of single molecule homogeneous line widths were measured in the maxima and in the wings of the inhomogeneous lines. The results indicate that in case of dodecane matrix the line broadening is caused by optical dephasing due to interaction with pseudolocal phonon modes. Exponential profile of temperature dependence of the line width gives the phonon energy of 23 cm(-1) In cases of tetradecane and hexadecane matrices there is additional broadening present which we interpret as spectral diffusion. Further, we present a new method for collecting the single molecule fluorescence using a selfoc micro lens.