Carbon disulfide,

PHYSICS · Subjective · Fermi University Physics · Mechanics & Dynamical Systems · Atomic, Molecular & Optical Physics · Oscillations and normal modes

Deriving the Spectrum, Ch Polyatomic molecules: normal modes and symmetry

Problem

Carbon disulfide,

\mathrm{S=C=S}

, is linear like carbon dioxide, with its symmetric stretch at

658\,\mathrm{cm^{-1}}

and its antisymmetric stretch at

1535\,\mathrm{cm^{-1}}

. Use this chapter's one-constant model of the two stretches, with

m_{\rm S}=31.972\,\mathrm u

and

m_{\rm C}=12.000\,\mathrm u

, to predict the ratio

\omega_3/\omega_1

. Compare it with the measured ratio, and say whether the model errs in the same direction, and by a similar fraction, as it did for carbon dioxide.