Clusters of styrene with several atoms and small
molecules were prepared and studied in a supersonic jet by
laser-induced fluorescence (LIF) from S1 and
resonance-enhanced multiphoton ionization (REMPI) using
S1
as the resonant intermediate state. The dissociation limit can be
determined in many cases (e.g., for argon,
CO2, and ammonia) by recording the excess energy at which
fluorescence from the cluster disappears and
styrene fluorescence appears. Parent ion signals are easily
observable from clusters excited to energies
exceeding the dissociation threshold in S1, as determined
by LIF. This indicates a relatively long lifetime of
the electronically excited cluster on the ionization time scale.
The styrene−trimethylamine system, which is
reactive in liquid solution, exhibits a very different fluorescence
behavior than all others. Two 1:1 styrene−trimethylamine clusters are observed by fluorescence excitation.
One of them exhibits locally excited emission
upon absorption near the origin, but at higher excitation energies, the
emission is exciplex-type. The other
shows exciplex emission at all excitation energies, including the 0−0
band. The data indicate at least two
nonradiative processes competing with exciplex formation and with its
radiative decay. The relation to solution
phase photochemistry is discussed.