高分辨偏正拉曼光谱对丙酸酐C=O振动模的拉曼光谱非一致效应研究

根据C=O振动的各向同性和各向异性拉曼光谱和红外光谱特点讨论研究了丙酸酐分子的局部有序排列以及振动耦合机理. 利用三级联共聚焦拉曼光谱仪测定了不同浓度丙酸酐的各向同性与各向异性拉曼光谱图, 分别采集了丙酸酐在四氯化碳和甲醇中的光谱以及不同极性溶剂中的光谱, 具体分析了丙酸酐C=O振动模的浓度效应、 溶剂效应以及拉曼光谱非一致效应(NCE). 结果表明, 丙酸酐C=O振动模的NCE效应随着浓度的降低而减小; 随着溶剂极性的减小而增加. 利用密度泛函理论的B3LYP-D3/31-311G(d,p)基组计算了丙酸酐单体和二聚体的几何稳定构型, 用聚集态理论模型解释了丙酸酐分子的NCE效应、 浓度效应与溶剂效应. 理论计算结果与实验结果相吻合.

Study on Raman Spectroscopy Non-coincidence Effect of Propionic Anhydride C=O Vibration Mode†

According to the isotropic and anisotropic Raman spectroscopy of C=O vibration and the characteristics of infrared spectroscopy, the local ordered vibration and coupling mechanism of propionic anhydride molecules were studied. The isotropic and anisotropic Raman spectra of different concentrations of propionic anhydride were determined by three-stage confocal Raman microspectroscopy. The spectra of propionic anhydride in carbon tetrachloride and methanol and the spectra in other solvents were collected. Concentration effects, solvent effects, and Raman spectroscopy non-coincidence effects(NCE) of propionic anhydride were analyzed in detail. The results show that the NCE effect of propionic anhydride decreases with decreasing concentration; the NCE value increases with the decreasing of solvent polarity. The geometrically stable configuration of propionic anhydride monomer and dimer was calculated by the density functional theory B3LYP-D3/31-311G(d, p) basis set. The NCE effect, concentration effect and solvent effect of propionic anhydride molecule were explained by the aggregation state theory model. The theoretical calculation results are in agreement with the experimental results.