分子极性对类胡萝卜素共振拉曼光谱的影响

摘要

测量了非极性分子β胡萝卜素和极性分子角黄素,在非极性溶剂CS2和极性溶剂1,2二氯乙烷中243—293 K的温度范围内的共振拉曼光谱。结果表明,溶质和溶剂的极性对拉曼光谱影响很大。非极性分子β胡萝卜素在非极性溶剂CS2中的拉曼散射截面最大,线宽最窄,而极性分子角黄素在极性溶剂1,2二氯乙烷中的拉曼散射截面最小,线宽最大。用溶剂效应及线性多烯分子的“相干弱阻尼电子-晶格振动”,“有效共轭长度”模型给予了解释。%The resonance Raman spectra of nonpolar molecule all-trans-β-carotene and polar molecule canthaxanthin in nonpolar CS2 and polar 1,2-dicholoroethane in a temperature range from 243K to 293K are measured. The results show that polarities of the solute and solvent have a great effect on Raman spectrum. Raman scattering cross-section of nonpolar all-trans-β-carotene in nonpolar solvent CS2 is biggest and its bandwidth is narrowest. Raman scattering cross-section of polar canthaxanthin in polar solvent 1,2-dicholoroethane is smallest and its bandwidth is widest. The experimental phenomena are explained by solvent effects, coherent weakly damped electron-lattice vibration and effective conjugated length.