维生素的太赫兹光谱数据库研究

发布时间：2018-01-10 02:32

本文关键词：维生素的太赫兹光谱数据库研究　出处：《南京林业大学》2015年硕士论文　论文类型：学位论文

【摘要】：太赫兹(THz)波是属于远红外波段的电磁频谱,位于微波和中红外波之间,有时被称为远红外波,是指频率在0.1~10THz范围内的电磁波(1THz=1012Hz)。THz辐射具有低能性,一般不会对生物分子的结构与活性造成损伤,此外还具有穿透性、指纹性等特征,使THz技术广泛应用于无损检测领域。傅里叶变换红外光谱技术FTIR(Fourier Transform Infrared Spectroscopy)是常见的太赫兹宽频带测量方法,用于测量各类材料和生物分子的光学特性,已被证实在低频段具有和太赫兹时域光谱仪(TDS)类似的灵敏度。分子的THz光谱包括分子内和分子间的共同作用,前者包括分子内基团的摇摆和转动、非共价键作用等,后者包括氢键作用、弱静电力以及范德华力等,同时受到分子与环境的相互作用力影响。研究证明除了太赫兹频段,远红外高频段、中红外、近红外频段的频谱对于研究生物分子的振动和转动特性也具有重要的指导意义。本文利用傅里叶变换红外光谱技术,对几种维生素样品进行了THz光谱研究,同时,尝试用Gaussian软件中的密度泛函理论(DFT)对实验结果得到的指纹谱的形成机制进行理论解释。本工作的研究内容主要包括实验测量和理论解析两方面,主要内容包括:1、通过傅里叶变换红外光谱系统,对吡哆素、生物素、核黄素、叶酸、维生素K2这几种常见维生素在太赫兹宽频段的光谱特性进行了研究。详细分析了维生素样品与聚乙烯粉末不同比例混合时的吸收光谱,将所得光谱进行比较,最后确定详实可靠的光谱图。结果表明它们在其有效波段内的光谱有很大差异,表现为吸收峰的个数、位置的差异。实验研究结果可用于建立维生素太赫兹光谱指纹数据库,也为后面章节理论解析维生素太赫兹光谱提供了依据。2、采用密度泛函理论(DFT)对叶酸和维生素K2的单分子模型进行模拟计算,并对其振动模式进行了指认。研究表明对于大部分固体维生素,它们的单分子模型模拟出的吸收峰的位置与实验存在一定差异,主要是由理论模拟采用的单分子模型与实验晶体样品结构的差异造成的。而核黄素单分子较晶胞分子的理论模拟,与实验测试结果一致性好,证明核黄素的吸收峰大都来自于分子内基团的振动。3、为了克服单分子模型模拟晶体维生素的局限性,分别对生物素和吡哆素的晶胞结构进行模拟计算,重点分析了生物素和吡哆素的单分子、二分子、三分子、以及晶胞分子的太赫兹光谱,阐明了分子内和分子间相互作用力的振动和转动机制,并对光谱吸收峰的振动模式进行了指认。
[Abstract]:Terahertz (THz) wave is a kind of electromagnetic spectrum in the far infrared band. It is located between the microwave and the middle infrared wave and is sometimes called the far infrared wave. The electromagnetic wave with frequency of 0.1 ~ 10THz has low energy and does not damage the structure and activity of biomolecules. In addition, it also has the characteristics of penetrability, fingerprint and so on. THz technology is widely used in the field of nondestructive testing. Fourier transform Infrared Spectroscopy (FTIR). Fourier Transform Infrared spectroscopyis a common terahertz broadband measurement method. Used to measure the optical properties of all kinds of materials and biomolecules. It has been proved that TDs have similar sensitivity to TDs at low frequency. The THz spectra of molecules include intramolecular and intermolecular interaction, the former includes the rocking and rotation of intramolecular groups. Non-covalent bond interactions, such as hydrogen bonding, weak electrostatic force and van der Waals force, are also affected by the interaction between molecules and the environment. It has been proved that in addition to terahertz band, far-infrared high frequency band, mid-infrared. The near infrared spectrum is also of great significance for studying the vibration and rotation characteristics of biomolecules. In this paper, the THz spectra of several vitamin samples are studied by Fourier transform infrared spectroscopy (FTIR). At the same time. Using density functional theory in Gaussian software. The formation mechanism of fingerprint spectrum obtained from the experimental results is explained theoretically. The research contents of this work mainly include two aspects: experimental measurement and theoretical analysis. The main contents include: 1, through Fourier transform infrared spectroscopy system, pyridoxine, biotin, riboflavin, folic acid. The spectral characteristics of vitamin K2 were studied in terahertz wide band. The absorption spectra of vitamin K2 mixed with polyethylene powder were analyzed in detail, and the spectra were compared. Finally, the detailed and reliable spectra are determined. The results show that their spectra in the effective band are very different, which is shown by the number of absorption peaks. The experimental results can be used to establish the vitamin terahertz spectrum fingerprint database and provide a basis for the theoretical analysis of vitamin terahertz spectrum in the following chapters. The single molecular model of folic acid and vitamin K2 was simulated by density functional theory (DFT) and its vibration mode was identified. The position of the absorption peak simulated by their monolayer model is different from that of the experiment. It is mainly caused by the difference between the monolayer model used in theoretical simulation and the structure of experimental crystal sample, while the riboflavin monolayer is in good agreement with the experimental results compared with the theoretical simulation of unit cell molecule. It is proved that the absorption peaks of riboflavin mainly come from the vibration of intramolecular group. In order to overcome the limitation of single molecular model simulating crystal vitamins, the unit cell structures of biotinyl and pyridoxine were simulated and calculated respectively. The terahertz spectra of single molecule, two molecule, three molecule and unit cell molecule of biotin and pyridoxine were analyzed, and the vibration and rotation mechanism of intramolecular and intermolecular interaction forces were elucidated. The vibrational modes of the spectral absorption peaks are also identified.
【学位授予单位】：南京林业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O441.4;O433

【引证文献】