Rotational coherence spectroscopy of para-difluorobenzene–Ar

We report the rotational coherence spectra (RCS) of the aggregate para-difluorobenzene–argon using time-resolved fluorescence depletion (TRFD). A newly constructed, broad range tunable solid-state picosecond laser system has been employed. The rotational constants (A+B)=2.2346±0.002 GHz have been obtained in excellent agreement with former high-resolution UV spectra [R. Sussmann, R. Neuhauser, H.J. Neusser, Can. J. Phys. 72 (1994) 1179]. The spectra show contributions of ground as well as excited state rotational coherences and demonstrate the applicability of RCS to analyze the structures of medium-sized molecular systems (substituted benzenes) and clusters.