Single molecule spectroscopy. Perylene in the Shpol'skii 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 as an excitation source. Fluorescence excitation spectra within the inhomogeneously broadened 0-0 absorption band around 443.8 nm were taken. The combination of high fluorescence quatumm yield and low intersystem crossing rate with a relatively short-lived triplet state allowed the direct observation of fluorescence photon bunches. The time distribution of the resulting emission gaps for the specific single molecule studied in detail leads to a triplet lifetime of τp = 1.1 ± 0.5 ms.