Raman Spectra of Van der Waals Dimers in Argon

A continuous band structure resembling an unresolved pure rotation band was observed in the Raman spectrum of high-purity gaseous argon. The wavelength corresponding to the peak of the band structure shifts with temperature in agreement with the theoretical shift of the pure rotation band of a diatomic molecule. The value of the rotational constant is in good agreement with that derived from data on the second virial coefficient for argon.