LaCl_3溶液中微团簇的光谱研究

Spectral Study of LaCl_3 in Aqueous Solutions

对LaCl_3溶液拉曼和荧光光谱及其变化进行了理论计算和实验研究,得到了较为全面的光谱信息。基于密度泛函理论的B3LYP方法,在6-31G(d,p)+Def2-SV(p)基组水平上计算了氯化镧溶液中的微团簇结构,结果表明微团簇分子趋向于形成9配位结构,验证了计算方法的可行性。理论拉曼光谱与实验光谱相比基本一致,随着LaCl_3的加入溶液拉曼光谱在300~600cm^(-1)范围内峰的强度稍微增大,原因可能为La—O振动与水中O—H的面内、面外摇摆峰叠加形成的;在3 000~4 000cm^(-1)范围内,氯化镧溶液与水相比峰形变窄,可能是由于在溶液中原有的水团簇结构破坏后形成的镧水合物中O—H的伸缩振动导致。荧光发射光谱在350nm处出现明显的新峰,且与浓度呈良好的线性关系,从络合物角度实现了对氯化镧溶液的定量分析;同样的基组水平上计算了团簇的荧光发射中心,在误差允许范围内,理论计算与实验值基本吻合,实现了对实验光谱中新峰的指认与归属。

In this study,the Raman and fluorescence spectra of LaCl3 solution were studied with theoretical calculation and spectroscopic experiments.Based on B3 LYP method of density functional theory,with the 6-31G（D,P）＋Def2-SV（P）based on the group level the lanthanum chloride solution of micro cluster structure is calculated.The results show that the micro cluster molecules tend to form a 9coordination structure,which verifies the feasibility of the method.Theoretical and experimental Raman values are compared to the basic consistent.The addition of LaCl3 leads to the increase of the peak intensity of the Raman spectra in the 300-600cm^-1 range,which may be caused by the superposition of the La-O vibration and the rocking peaks of O—H in aqueous solutions;In the 3 000-4 000cm^-1 range,the peak of lanthanum chloride solution is narrow compared with water,which may be caused by the stretching vibration of O—H in lanthanum hydrate.Fluorescence emission spectra at 350 nm appear obvious new peak,the good linearity was obtained between the peak intensity and the concentrations,and a rapid method for the quantitative analysis of lanthanum chloride solution from the angle of the complex is also realized.On the same basis set level calculated fluorescence emission center of clusters,in the range of allowable error,the theoretical calculation and the experimental spectra are basically consistent,and the new peak of the experimental spectra are identified.