[Explanation of C=O of acetone changing in solvents by some models].

Raman spectra of acetone's carbonyl stretching in 16 solvents were measured, and were also calculated by self-consistent reaction field (SCRF) method in Gaussian03. The frequency shift in experiment was analyzed by donor-acceptor model, Kirkwood model and SCRF model respectively. Among them, the donor-acceptor model can explain the shift very well. The SCRF method can do it also, while not as well as the donor-acceptor model, but is better than Kirkwood model. Correlating the mechanisms of the 3 methods, it was found that the donor-acceptor model is powerful in explaining the vibrational spectra of molecular bond, which is nucleophilic reagent. The SCRF model considers not only the influence of dielectric constant epsilon, but also the influence of the bulk and the structure of molecule etc. Although the model is complex and difficult to calculate, but it takes many factors into account, so the calculated results accord with experiment better than the Kirkwood model. The main parameter of the Kirkwood model is epsilon, so it is very simple and easy to calculate, nonetheless the trend of frequency shift can still be reflected, indicating that the dielectric constant epsilon is a main character affecting the frequency shift.

[Study of the Raman spectrum of CCl4 Fermi resonance].

Fermi resonance is a very common phenomenon in molecule vibration spectra, especially in polyatomic molecule with complex structure. Fermi resonance appears when a fundamental vibration frequency lies closely to an overtone or combination frequencies. One can observe two peaks coming from Fermi resonance and the energy transfer also occurs between the two peaks. Fermi resonance phenomenon appears in both infrared spectrum and Raman spectrum. The Raman spectrum of CCl4 was measured. The frequency separation between the two peaks in a Fermi resonance doublet was observed and the integrated intensities were calculated with the software of Origin Pro 7.5. Fermi resonance interaction was caused by the CCl4 C-Cl f-symmetrical stretching fundamental nu3 coupling. The combination frequency (nu1 + nu4) of C-Cl a1-symmetrical stretching nu1 and band C-Cl2 f-symmetrical bending nu4 was calculated. Based on Bertran's theory, Fermi coupling coefficient W was calculated and the theoretical value nu3(0) of nu3 was estimated. The present article provided good reference for better understanding of the relationship between molecular vibration frequency and molecular structure.