β胡萝卜素是一种重要的共轭多烯生物分子,其在光电器件与功能材料等研制方面有重要应用.本文利用金刚石对顶砧技术,在0～0.60 GPa的压强范围下,分别对β胡萝卜素溶于水和二硫化碳溶液进行了原位拉曼光谱测量,比较了二者的拉曼频移和半高宽等光谱特性。实验结果表明,两种样品的拉曼频移均随着压强的增加而向高波数方向移动,半高宽也随之增加.引用线性链状多烯分子的两种理论模型,即 “相干弱阻尼电子-晶格振动模型”和 “有效共轭长度模型”等理论给予了解释.其机理是由于压力的增加,β胡萝卜素分子被压缩,结构有序性下降,有效共轭长度减小,拉曼活性降低,碳碳键的相干弱阻尼电子-晶格振动减弱.CC键的键长变短,因此拉曼蓝移;CC键的键长差增加,从而使半高宽增加.此外,由于β胡萝卜素溶于非极性溶剂CS2溶液中,受到周围溶剂分子的作用,使溶质与溶剂之间的色散力作用对压力更敏感一些,从而使得其拉曼频移和半高宽随压强变化的斜率要比溶于水中的大.为研究共轭多烯分子在外场下的分子结构变化以及溶剂中分子的存在形式等具有一定的应用价值。

β-carotene is an important kind of polyene biomolecules,which has significant applications on researching optoelectronic and functional materials.In-situ high pressure Raman spectra of β-carotene are measured in CS2 solution and water respectively at pressure range from 0～0.60 GPa.Then we compared both of them the Raman shift and CC bond of the full width at half maximum(FWHM) of the Raman spectra.It is therefore concluded that both of the samples’ Raman shift moved to the high wave number and the full width at half maximum increased depending of the pressure.The experiment phenomena were interpreted by the theory of “coherent weakly damped electronic-lattice vibration model” and “effective conjugation length model”.The mechanism is that the β-carotene is compressed and has the lower structure order,shorte the effective conjugation length,decreased Raman active,weaker the coherent weakly damping CC bond vibration in high pressure.Because of the CC bond length become short,so the Raman spectra are found to blueshift.The CC bond of the full width at half maximum(FWHM) of the Raman spectra increased is attributed to the increase of difference in C—C and CC bond lengths.Moreover,due to dissolving in non-polar CS2 solvent,the β-carotene encounters the interaction of the surrounding solvent molecules.So the dispersion force interaction between solute and solvent is more sensitive to pressure.Then it makes that the slop of Raman shift and the full width at half maximum in the CS2 solution are faster than dissolved in water with increasing pressure.This paper provides an application value for research on molecular structure change under the external field and the presence form of polyenes biomolecules in the solvent.