摘要
In this work,we measure the Raman scattering cross sections（RSCSs） of the carbon-carbon（CC） stretching vibrational modes of canthaxanthin in benzene,acetone,n-heptane,cyclohexane,and m-xylene.It is found that the absolute RSCS of CC stretching mode of canthaxanthin reaches a value of 10 24 cm ^-2 ·molecule ^-1 ·sr ^-1 at 8×10 ^-5 M,which is 6 orders of magnitude larger than general RSCS（10 30 cm 2 ·molecule 1 ·sr 1）,and the RSCSs of canthaxanthin in various solvents are very different due to the hydrogen bond.A theoretical interpretation of the magnetic experimental results is given,which is introduced in a qualitative nonlinear model of coherent weakly damped electron-lattice vibration in the structural order of polyene chains.In addition,the optimal structure and the bond length alternation（BLA） parameter of canthaxanthin are calculated using quantum chemistry calculation（at the b3lyp/6-31g（d,p） level of theory）.The theoretical calculations are in good agreement with the experimental results.Furthermore,the combination of Raman spectroscopy and the quantum chemistry calculation study would be a quite suitable method of studying the structures and the properties of the π-conjugated systems.
In this work,we measure the Raman scattering cross sections（RSCSs） of the carbon-carbon（CC） stretching vibrational modes of canthaxanthin in benzene,acetone,n-heptane,cyclohexane,and m-xylene.It is found that the absolute RSCS of CC stretching mode of canthaxanthin reaches a value of 10 24 cm ^-2 ·molecule ^-1 ·sr ^-1 at 8×10 ^-5 M,which is 6 orders of magnitude larger than general RSCS（10 30 cm 2 ·molecule 1 ·sr 1）,and the RSCSs of canthaxanthin in various solvents are very different due to the hydrogen bond.A theoretical interpretation of the magnetic experimental results is given,which is introduced in a qualitative nonlinear model of coherent weakly damped electron-lattice vibration in the structural order of polyene chains.In addition,the optimal structure and the bond length alternation（BLA） parameter of canthaxanthin are calculated using quantum chemistry calculation（at the b3lyp/6-31g（d,p） level of theory）.The theoretical calculations are in good agreement with the experimental results.Furthermore,the combination of Raman spectroscopy and the quantum chemistry calculation study would be a quite suitable method of studying the structures and the properties of the π-conjugated systems.
基金
Project supported by the National Natural Science Foundation of China (Grant Nos. 11004252 and 10974067)
the National Basic Research Program of China (Grant No. 2012CB722802)
