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The depolarized Raman 2ν3 overtone of CO2: a line-mixing shape analysis
I A Verzhbitskiy1, A P Kouzov, F Rachet
1MolTech-Anjou, UMR CNRS 6200, Université d'Angers, 2 Boulevard Lavoisier, 49045 Angers, France.
The Journal of Chemical Physics
|May 24, 2011
Summary
This study analyzes the depolarized Raman spectrum of carbon dioxide (CO2) overtone. A sophisticated model accurately predicts spectral shapes, accounting for line mixing effects, crucial for understanding gas properties.
Area of Science:
- Molecular Spectroscopy
- Physical Chemistry
- Quantum Mechanics
Background:
- Previous work established the depolarized nature of the 2ν(3) transition in carbon dioxide (CO2).
- Understanding overtone transitions is vital for molecular property determination.
Purpose of the Study:
- To perform a first-principles shape analysis of the depolarized Raman spectrum of CO2 at room temperature.
- To develop and validate a sophisticated model for accurate spectral analysis, considering line mixing.
Main Methods:
- Initial analysis used a simplified model with isolated Lorentzian line shapes.
- A more advanced approach based on the extended strong-collision model was developed.
- The models were applied to analyze the depolarized Raman spectrum of CO2 at various densities.
Main Results:
- The simpler model showed deviations from experimental data, especially at higher CO2 densities.
- The sophisticated model achieved striking agreement with measured spectra across all densities.
- Accurate rotational line broadening coefficients were calculated without arbitrary parameters.
Conclusions:
- The extended strong-collision model effectively accounts for heavy line mixing in CO2 Raman spectra.
- This approach provides accurate spectral predictions and reliable molecular parameters.
- Vibrational shift data, linearly dependent on gas density, were also determined.
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