Line interference effects have been observed in the rotational Raman spectrum of the nearly prolate, asymmetric top C2H4at pressures sim;1 atm. An interferometric detection scheme is used which enhances the contribution of quasiperiodic, symmetrichyphen;tophyphen;allowed lines to the spectrum. A simple, cluster model provides an adequate description of interference effects in these lines. Optimum values of the cluster spectral window and width parameters are determined from a leasthyphen;khgr;2fitting between experimental and theoretical Raman interferogram spectra. The value obtained for the cluster linewidth is in good agreement with the results of previous experiments on C2H4, and provides a physically meaningful alternative to theadhocline shape introduced to account for the presence of nonhyphen;Lorentzian line shapes in this latter spectra. The cluster model is also compared with the results of a model calculation of interference effects in a simple spectrum.
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