Styrene Clusters in a Supersonic Jet:  Reactive and Nonreactive Systems

Abstract

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.

Vibrational and Electronic Spectroscopy of the 4-Hydroxystyrene−CO2 Cluster and Its Hydrate: A para-Coumaric Acid Impostor

“…The observed blue shift matches well observations for other CO 2 clusters of benzene derivatives. For example, the phenol−CO 2 cluster has its origin displaced by +38 cm −1 , and in the case of styrene, a shift of +51 cm −1 is observed . Similarly, we find that the spectrum detected at m / e = 184 (Figure c) is also reminiscent of the p VP spectrum, although now a red shift of −79 cm −1 is observed.…”

Dual Emission of 4-(1H-Pyrrol-1-yl)benzonitrile Clusters with Acetonitrile in a Supersonic Jet and Its Absence in Phenylpyrrole Clusters

“…Size Dependence of LE and CT Emission. The detailed energy requirements for the different processes could not be established for this system (in contrast with others , ), as the excitation spectra are devoid of vibrational structure. The congested character of the spectrum (recall that the systems are jet-cooled) is most probably due to overlap between slightly different absorption spectra due to several clusters differing in size and structure.…”

“…The experimental setup is a modification of the setup described in ref . The vacuum chamber consisted of a 6 in.…”

Resonant Two-Photon Ionization Spectroscopy of Styrene (Methanol)nClusters,n= 1−9

“…In contrast to benzene, few studies of clusters containing styrene have been reported. ,− Clusters of styrene with Ar, N 2 , CO 2 , NH 3 , and trimethylamine were studied by laser-induced fluorescence (LIF) and REMPI. ,− The origin bands of these clusters are shifted by −31, −25.5, +51, +52, and −24 cm -1 relative to the band of the bare styrene molecule. The spectra of the styrene−TMA 1:1 cluster were assigned to two isomeric forms, both capable of forming a charge-transfer complex upon excitation to the locally excited state. , We recently reported the REMPI spectra of styrene (water) n clusters, SW n , with n = 1−2, which indicate that the origin of the SW complex is blue shifted by −22 cm -1 relative to the band of the bare styrene molecule …”