己酸乙酯分子的振动光谱研究

采用B3LYP混合泛函和6-31G基函数组，并对重原子和轻原子使用离散函数和极化函数,　利用密度泛函理论（density functional theory, 简称DFT）计算了己酸乙酯的分子振动光谱，并以此为依据，首次对实验测得的己酸乙酯（Ethyl hexanoate）分子的正常拉曼光谱（NRS）和红外光谱(IR)进行了指认，对己酸乙酯分子的振动模式进行了归属。理论计算和实验数据的比较分析表明，理论计算结果的拉曼和红外各振动峰位与实验测量结果符合得较好。最后，分别把拉曼光谱和红外吸收谱中较强的峰位指认为己酸乙酯分子的拉曼特征峰和红外吸收的特征峰。己酸乙酯分子振动光谱的上述研究，可能在白酒调香，化工和生物等领域的检测方面具有广泛的应用，对进一步拓宽己酸乙酯分子的研究领域具有一定的参考价值。

Study on Vibrational Spectra of Ethyl Hexanoate Molecule

The vibrational spectra of ethyl hexanoate were calculated by the density functional theory(DFT) with B3LYP complex function, diffuse function and polarization function added to heavy atoms and light atoms. On the base of this, the normal Raman spectrum(NRS) and the infrared spectrum(IR) were assigned in detail in the present paper. Comparing the calculated results with the experimental data, the calculated results are in good agreement with the experimental results. The comparison of the experimental Raman and infrared spectra shows that in the experimental Raman spectrum, the strongest bands appear at the frequencies of 2 600-3 100 cm-1, while the strongest band is not 1 734 cm-1 but 1 444 cm-1 at the frequencies of 400-2 000 cm-1. The band 1 734 cm-1 attributed to the CO stretch vibration is the distinctive mark of organic ester compounds, and the band 1　444 cm-1 is related to the symmetric and anti-symmetric scissors vibration of C—H. In the experimental infrared spectrum, the strongest vibrational band is 1 739 cm-1, which is related to CO stretch vibration; At the frequencies of 400-2 000 cm-1, the relative intensity of the infrared spectrum is distinctively stronger than that of the Raman spectrum, but the relative intensity of infrared spectrum is weaker than that of the Raman spectrum at the frequencies of 2 600-3 100 cm-1. In the frequencies of 2 600-2 800 cm-1, the vibrational bands 2 762 and 2 732 cm-1 do not appear in the experimental spectra, which may originate from two reasons: (1) the weak interaction of molecules. Also, the relative intensity of these vibrational bands is very weak in the experimental spectra, and this may testify that the interaction of molecules is rather weak; (2) the vibrational bands may belong to second order vibrational mode at the frequencies of 2 600-2 800 cm-1. The relative intensity of infrared bands is weaker than that of the Raman bands at the frequencies of 2 600-2 800 cm-1. At the end, the stronger bands appearing in Raman and infrared experimental spectra are assigned as characteristic marks, respectively. The study on vibrational spectra of ethyl hexanoate molecule may have great application value in detection of liquor flavor, chemical industry and biology fields, providing important reference value for the related basic research field.