Amendment to bertran equation and the weak Fermi resonance characteristic of CS2 in C6H6

The Raman spectra of CS 2 in C 6 H 6 is messured and the Fermi resonance of v 1 —2 v 2 in solution and in pure CS 2 is obvionsly different.The characteristic parameters are calculated by Berttern equation.It was found that with the concentration of CS 2 declining,the ratio of the spectral intensity （ R = Ｉ 655 / I 796 ） decreases and the coupling coefficient （ Ｗ ） raises, and the other parameters also change correspondingly. The analysis shows that dissipation coefficient of v 0 1 of CS 2 is affected by the concentration of C 6 H 6 . Asymmetric frequency shift of v 0 1 and 2 v 0 2 are observed in experiment,which is explained by amending the Bertran theory. This report has reference value for the molecule spectrum certification and the understanding and use of Fermi resonance theory.