Application of derivative method in teaching of MIR spectroscopy
Chang Ming1, Wang Qian2, Zhang Bihan2, Li Zeteng1, Zhang Meihuan1, Yu Hongwei1, Xu Yuanyuan1
1. College of Chemical Engineering, Shijiazhuang University, Shijiazhuang 050035, China; 2. College of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China
摘要 以医用白凡士林为例，通过导数法对中红外光谱数据进行处理。采用一维中红外光谱，结合一阶导数 MIR 光谱、二阶导数 MIR 光谱、三阶导数 MIR 光谱和四阶导数 MIR 光谱，对医用白凡士林进行了结构研究。结果表明，医用白凡士林分子主要存在CH3 不对称伸缩振动模式（ν■）、CH2 不对称伸缩振动模式（ν■）、CH2 对称伸缩振动模式（ν■）、CH3 不对称变角振动模式（δ■）、CH3 对称变角振动模式（δ■）、CH2 面内摇摆振动模式（ρ■）等。二阶导数 MIR 光谱的谱图分辨能力要优于相应的一维 MIR 光谱和四阶导数 MIR 光谱。选择适宜的平滑点数，可有效提高导数光谱的分辨能力，为拓宽中红外光谱的应用领域提供理论支撑和实践应用借鉴。
Abstract： Taking medical white vaseline as an example, the MIR spectrum data were processed by derivative method. The structure of medical white vaseline was studied by using one-dimensional MIR spectrum combined with first derivative MIR spectrum, second derivative MIR spectrum, third derivative MIR spectrum and fourth derivative MIR spectrum. The results show that the medical white vaseline molecule mainly exists CH3 asymmetric stretching vibration mode(ν■), CH2 asymmetric telescopic vibration mode (ν■), CH2 symmetric telescopic vibration mode (ν■), CH3 asymmetric variable angle vibration mode (δ■), CH3 symmetrical variable angle vibration mode (δ■), CH2 in-plane rocking vibration mode (ρ■). The spectral resolution of the second derivative MIR spectrum is better than that of the corresponding one-dimensional MIR spectrum and the fourth derivative MIR spectrum. Choosing appropriate smoothing points can effectively improve the resolution ability of derivative spectrum, and provide theoretical support and practical application reference for expanding the application field of MIR spectrum.
