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Updated: Jul 7, 2026

Rejection of Fluorescence Background in Resonance and Spontaneous Raman Microspectroscopy
Published on: May 18, 2011
[Study of the Raman spectrum of CCl4 Fermi resonance]
Shu-qin Gao1, Jia-ning He, Rong-fu Li
1Department of Physics, Jilin University, Changchun 130023, China. shuqin_gao@163.com
Abstract:
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.
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