INFRARED SPECTROSCOPY OF BENZENE-HCN IN HELIUM-DROPLETS
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Date
2001
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Ohio State University
Abstract
Infrared spectra are reported for several $(C_{6}H_{6})_{m}-(HCN)_{n}$ and $(C_{6}D_{6})_{m}-(HCN)_{n}$ clusters in liquid helium nanodroplets. A large electric field can be used to collapse the rotational structure in these spectra, which aids in the initial searching. In the 1:1 clusters the $HCN_{\nu CH}$ stretching vibration at $3253.2 cm^{-1} (C_{6}H_{6}-HCN)$ and $3252.9 cm^{-1} (C_{6}D_{6}-HCN)$ are red-shifted by approximately $60 cm^{-1}$ compared to the monomer, indicative of strong intermolecular hydrogen bonds between the CH-group and the aromatic $\pi$-clouds of the benzenes. Zero field spectra show considerable rotational structure consistent with a symmetric rotor structure as determined in the gas-phase by microwave $spectroscopy.^{a}$ Moreover several trimers and tetramers of HCN and Benzene have been observed, all of which are further red-shifted than the 1:1 complexes. Pressure-dependency studies allow the size assignments of these clusters. The frequency shifts and rotational contours of the bands allows one to infer the structures of these clusters in liquid helium.
Description
$^{a}$H.S. Gutowski, E. Arunan, T. Emilson, S.L. Tschopp, and C.E. Dykstra, J. Chem. Phys. 103(1995), 3917.
Author Institution: University of North Carolina; Department of Chemistry, University of North Carolina
Author Institution: University of North Carolina; Department of Chemistry, University of North Carolina