Sulfur dioxide vibrational modes

Estimate the molar heat capacity (at constant volume) of sulfur dioxide gas. In addition to translational and rotational motion, there is vibrational motion. Each vibrational degree of freedom contributes R to the molar heat capacity. The temperature needed for the vibrational modes to be accessible can be approximated by 6 = />vvih/, where k is Boltzmann s constant. The vibrational modes have frequencies 3.5 X... 

Excited Vibrational Spectrum of Sulfur Dioxide. II. Normal to Local Mode Transition and Quantum Stochasticity. 

The investigation of how sulfur atoms in 1,2,4-trithiolane become oxidized to sulfoxide groups showed that 1 molar equiv of MCPBA in CH2CI2 yields both isomers in comparable amounts, but only the compound with the thioether S=0 group could be isolated pure <2004ICA(357)1897>. With an excess of MCPBA, the dioxide that was obtained had a trans-structure, as shown by X-ray analysis (Scheme 75). Ab initio calculations were performed for the geometry and vibrational modes of the new compounds <2004ICA(357)1897>. 

It is of interest to compare the spectrum of carbon dioxide with iliai of a nonlinear Irialomic molecule such as water sulfur dioxide, or nitrogen dioxide. These molecules have (3x3)- 6 3 vibrational modes that lake the followine forms ... 

Sulfur dioxide is a nonlinear molecule. How many vibrational modes w ill this compound have How many IR absorption bands would sulfur dioxide be expected to have ... 

Often, as in the foregoing examples, parts of Raman and IR spectra are complementary, each being associated with a different set of vibrational modes within a molecule. For nonccnirosymmetric molecules, many vibrational modes may be both Raman and IK active. Forcxample,aIlof the vibrational modes of sulfur dioxide yield both Raman and IR bands. The intensities of the hands differ, however, becau.se tlic probabilities for the transitions are different for the two mechanisms. Raman spectra arc often simpler than IR spectra be cause the occurrence of overtone and combination bands is rare in Raman spectra. 

Figure 11.73 shows the vibrations in the sulfur dioxide molecule. Sulfur dioxide and carbon dioxide molecules have different shapes, and hence the vibrations causing changes in the dipole moment differ. The vibrational modes of sulfur dioxide are similar to those of water. ... 

Rgure 22.6 Vibrational Normal Modes, (a) Caibon dioxide, (b) Sulfur dioxide. 

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