由于β胡萝卜素分子具有光敏感的特性, 同时也具有光采集、 光防护功能, 是重要的光电材料, 所以在光器件和光控温方面有重要应用。 线性多烯分子的共振拉曼光谱是π电子能隙对碳碳键振动调制的结果, 这种调制作用与外场有关, 研究其在外场下的分子结构和性能变化既有理论意义也有应用价值。 测量了β胡萝卜素分子在环己醇中341～275 K温度范围内的紫外-可见吸收光谱和共振拉曼光谱。 实验结果表明随着温度的降低, 黄琨因子和碳碳键的每个振动模的电子-声子耦合常数减小, 紫外-可见吸收光谱红移, 碳碳键拉曼散射截面增加。 295 K时溶液从液相转为固相, 溶液相变后, β胡萝卜素分子的构型变化特征能ε变大, 且使固相中的黄琨因子、 紫外-可见吸收峰波长、 电子-振动耦合系数、 拉曼散射截面都随着温度的降低变化率增加。 固相中的黄琨因子比液相中的黄琨因子大一个数量级。 液相中的构型变化特征能为εａ=0.206 7 eV, 固相中的构型变化特征能为εb=0.559 6 eV, 构型变化特征能增加, 使有效共轭长度n(T)＝n0exp(ε/kT)随温度的降低而增加的速率变大; 导致π电子能隙减小加快, 电子能隙对β胡萝卜素分子碳碳键振动的调制作用增强, 电子振动耦合系数增加, 拉曼散射截面大幅增加。

All-trans-β-carotene has important functions of light collection and light protection, and it is also an important electro-optical material. The Raman spectra of polyenes are a result of the modulation effect of the π electron energy gap on the vibration of CC bonds, which associate with the external field. So it has higher theoretical significance and practical value to study the molecular structure and properties change under the external field. Ultraviolet-visible absorption spectra and resonant Raman spectra of all-trans-β-carotene in cyclohexanol were measured from 341 to 275 K. The liquid-solid phase transition of the sample appears at 295 K. The characteristic energy describes the conformational change of all-trans-β-carotene molecule. After the solution phase transition, the characteristic energy ε of all-trans-β-carotene molecule becomes bigger. And when temperature decreasing, the rate of change of the Huang-Rhys, the wavelength of UV absorption peak, electron-phonon Parameter, RSCSs of the CC bond increase. the Huang-Rhys in solid phase is an order of magnitude higher then liquid phase. The characteristic energy of liquid is 0.206 7 eV. The characteristic energy of liquid is 0.559 6 eV. The increasing of the characteristic energy ε makes the rate of increasing of the effectively conjugated length becomes bigger. The decreasing of the π electric energy gap quickens. The function of moderation from electron energy gap to all-trans-β-carotene molecule enhances. Electron-phonon Parameter increases. RSCSs of the CC bond substantially increases.