Journal of Physical Chemistry A, Vol.111, No.20, 4252-4258, 2007
Fluorescence studies of terrylene in a supersonic jet: Indication of a dark electronic state below the allowed transition
Jet-cooled terrylene has been studied in helium buffer gas using a pulsed nozzle by means of laser-induced fluorescence. Fluorescence excitation and two-color depletion experiments (resulting in hole burning spectra) are presented. Analysis of the spectra leads to the conclusion that another excited electronic state is present in the vicinity of the allowed B-1(1u) state. Assuming (according to previous literature suggestions Karabunarliev, S.; Baumgarten, M.; MUllen, K. J. Phys. Chem. A 1998, 102, 7029) that this dark state is the 2(1)A(g) state, we discuss the vibrational structure of the fluorescence excitation spectrum in terms of two manifolds of vibronic states belonging to S-d(2(1)A(g)) and S-1(B-1(1u)) states. The anomalous shift between excitation and dispersed fluorescence spectra observed earlier for terrylene in a neon matrix is discussed as a consequence of terrylene electronic relaxation to the low-energy dark state.