导数法在石蜡油分子结构中红外光谱实验教学中的应用OA

The molecular structure of paraffin oil was studied using mid infrared(MIR)spectroscopy(including one-dimensional MIR spectroscopy,first-order derivative MIR spectroscopy,second-order derivative MIR spectroscopy,third-order derivative MIR spectroscopy,and fourth-order derivative MIR spectroscopy).The experiment found that the infrared absorption mode of paraffin oil molecular structure mainly includes:CH3 group asymmetric stretching vibration mode(νasCH3-paraffin oil),CH3 group symmetric stretching vibration mode(νsCH3-paraffin oil),CH2 group asymmetric stretching vibration mode(νasCH2-paraffin oil),CH2 group symmetric stretching vibration mode(νsCH2-paraffin oil) CH2 group bending vibration mode(δCH2-paraffin oil),CH3 groups asymmetric bending vibration mode(δasCH3-paraffin oil),CH3 groups symmetric bending vibration mode(δsCH3-paraffin oil)and CH2 group in-plane rocking vibration mode(ρCH2-paraffin oil).Research has found that the molecular structure of paraffin oil spectral resolution of second-order derivative MIR spectroscopy is superior to corresponding one-dimensional MIR molecular spectroscopy,first-order derivative MIR spectroscopy,third-order derivative MIR spectroscopy,and fourth-order derivative MIR spectroscopy.Selecting appropriate smoothing points(including 5 smoothing points,9 smoothing points,13 smoothing points,19 smoothing points,25 smoothing points,37 smoothing points,49 smoothing points,and 149 smoothing points)can effectively improve the resolution ability of second-order derivative MIR spectra,providing theoretical support and practical application reference for expanding the application field of MIR spectroscopy in clinical medicine.