Abstract

Resonant two-photon ionization time-of-flight mass spectrometric studies of the series of clusters C₆H₆−(H₂O)_n, C₆H₆−(CH₃OH)_n, and C₆H₆−(CH₃0H)_m(H₂O)_n have been carried out via the S₁←S₀ transition of C₆H₆. Using a combination of rotational band contour analysis in the smaller clusters and vibronic level arguments in the larger clusters, we have been able to constrain the general structural features of these clusters. The comparison of the spectroscopy of C₆H₆−(H₂O)_n with that of C₆H₆(CH₃OH)_n shows strong similarities for clusters with n = 1 and n = 2 but significant differences for larger clusters. The picture of these clusters that is emerging places the solvent molecules in a hydrogen-bonded network that builds off one side of the benzene ring. Broadly classified, the structures fall into two classes involving either cyclic or chain-like hydrogen bonded clusters of solvent molecules. We argue that the differences between C₆H₆−(H₂O)_n and C₆H₆−(CH₃OH)_n clusters are a consequence of dangling O−H's in the water cluster, which are not present in the methanol cluster. Similar data on the mixed C₆H₆−(H₂O)_m(CH₃OH)_n clusters will also be presented.

© 1992 Optical Society of America