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We have determined the Raman scattering cross sections(RSCSs) ofβ-carotene for C=C and C—C stretching modes,with the 1444 cm~(-1) Raman band of cyclohexane as internal standard,in different solvents at low concentrations by measuring Raman intensity.The results show that RSCSs ofβ-carotene were 10~6—10~7 times larger than the general RSCSs,we analyzed that this enhancement was caused not only by the resonance Raman effect but also by nonlinear coherent CC vibration in aqueousβ-carotene.Moreover,overtone and combinations of it were also observed and their intensities were 10%—20%of those of their fundamentals whenβ-carotene was dissolved in non-polar solvents,respectively.
We have determined the Raman scattering cross sections (RSCSs) of β-carotene for C = C and C-C stretching modes, with the 1444 cm -1 Raman band of cyclohexane as internal standard, in different solvents at low concentrations by measuring Raman intensity. These results show that RSCSs of β-carotene were 10 ~ 6-10 ~ 7 times larger than the general RSCSs, we analyzed that this enhancement was caused not only by the resonance Raman effect but also by nonlinear coherent CC vibration in aqueous β- carotene. Moreover, overtone and combinations of it were also observed and their intensities were 10% -20% of those of their fundamentals when β-carotene was dissolved in non-polar solvents, respectively.