Selective spectroscopy of terrylene in incommensurate matrix of biphenyl

The technique of total luminescence spectroscopy is applied to study a low-temperature (image) bulk polycrystalline sample of biphenyl doped with terrylene at 10−5 mol/mol concentration. From the two-dimensional excitation-fluorescence spectra, the shape of inhomogeneous distribution function of the purely electronic transition energy of impurity molecules is obtained, revealing unusually broad (for other hosts) distribution of several hundreds of cm−1. Well-defined vibronic replicas of the zero-phonon lines are observable with frequencies well correlated with excitation frequency, thus reflecting the vibrational spectrum of terrylene. Additionally, we observe broad bands that cannot be interpreted as phonon sidebands because of virtually absent correlation with zero-phonon lines. These bands can be attributed to relaxation specific for incommensurate biphenyl matrix.