Rotational-vibrational lines

Figure 1. Rotational—vibrational line strength correction factors for pure rotational Raman scattering (fM)0 and for O-, S-, and Q-branch vibrational Raman scattering (foh fots, and folQ). The value J is the rotational quantum number of the initial level (O), Stokes (A), anti-Stokes.

High resolution studies by conventional spectroscopy are genuinely hampered by Doppler-broadening of the rotation-vibration lines in the low pressure regime. Individual Doppler-shifted frequencies contribute to the (normalized) Doppler-broadened line shape, due to the distribution of molecular velocities along the direction of observation... 

Figure 4.3-2 Assignment for the rotation-vibration lines of the CO fundamental vibration band.

For clarity, the wavenumber scale of the CH-stretching region is magnified besides the A type band at 2989.5 cm (t n), there is a B type band at higher wavenumbers whose rotation-vibration lines go through a marked intensity minimum (3105.5 cm ( 9). Further two A type bands of medium intensity (1443.5 cm 1 12 and a combination band at 1889.6 cm, assigned to r v -f i s) can be observed. 

The positions of individual rotational-vibrational lines, which are known for both the first and the second overtone of gaseous CO, may be used to describe the vibrational bandshape at high density. According to a model developed by Bouanich et al. (1981, 1983), the band contour, expressed as the reduced molar absorption coefficient e , is calculated as the sum of the individual lines in the gas phase spectrum. 

In the paper of Madeja and Havenith the observation of 409 lines in the frequency range from 1241.7 to 1250.7 cm i was reported. All lines could be assigned to the C-O stretch vibrational band. The splitting due to proton transfer tunneling was fully resolved (see Fig. 2.3). The frequency range from 1241.6 to 1242.6 cm is displayed it can cdearly be seen that each rotational vibrational line is split into two fully resolved tunneling components. 

The main infrared lines are the rotation-vibration lines of molecules, mostly CO in the photosphere. Many other molecules... 

---