[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 2600-3100 cm(-1), while the strongest band is not 1734 cm(-1) but 1444 cm(-1) at the frequencies of 400-2000 cm(-1). The band 1734 cm(-1) attributed to the C=O stretch vibration is the distinctive mark of organic ester compounds, and the band 1444 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 1739 cm(-1), which is related to C=O stretch vibration; At the frequencies of 400-2000 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 2600-3100 cm(-1). In the frequencies of 2600-2800 cm(-1), the vibrational bands 2762 and 2732 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 2600-2800 cm(-1). The relative intensity of infrared bands is weaker than that of the Raman bands at the frequencies of 2600-2800 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.