SINGLE-MOLECULE SPECTROSCOPY, PERYLENE IN THE SHPOLSKII MATRIX N-NONANE

Single perylene molecules in the Shpol'skii matrix n-nonane have been investigated at 1.7 K using a frequency-doubled cw Ti:sapphire laser a s an excitation source. Fluorescence excitation spectra within the inh omogeneously broadened 0-0 absorption band around 443.8 nm were taken. The combination of high fluorescence quantum yield and low intersyste m crossing rate with a relatively short-lived triplet state allowed th e direct observation of fluorescence photon bunches. The time distribu tion of the resulting emission gaps for the specific single molecule s tudied in detail leads to a triplet lifetime of tau(p) = 1.1 +/- 0.5 m s.