氨基酸的太赫兹光谱及其振动模式研究

【作者】 王雪美；

【导师】 王卫宁；

【作者基本信息】 首都师范大学 ， 光学， 2008， 硕士

【摘要】 太赫兹(THz )辐射是指频率位于微波和红外光之间的电磁辐射,属于远红外波段。近十几年来,超快激光技术的迅速发展,为THz脉冲的产生提供了稳定、可靠的激发光源,使THz辐射的产生和应用研究得到了蓬勃发展。太赫兹时域光谱(THz-TDS)技术作为一种崭新的THz探测技术,近年来在光谱和成像方面得到了广泛应用,由于生物分子的振动-转动能级落在THz波段,而且THz本身具有低能性,不会对生物组织造成破坏等特点,使得THz对生物材料的无损检测成为研究的热点之一。目前THz-TDS技术在若干生物分子的研究中取得了很好的实验结果,但相应的光谱分析研究还不成熟,寻找合适的理论模拟软件和方法对于合理和完善的解释THz光谱的形成机制具有重要的意义。本论文主要是采用理论模拟与实验相结合的方法研究蛋氨酸、苏氨酸等五种蛋白质氨基酸的THz光谱并对其在0.2-2.8THz波段的吸收进行了详细的归属和讨论。采用THz-TDS技术,获取它们可靠的THz吸收光谱。选取剑桥数据库分子模型,应用Gaussian03软件,选取DFT理论等不同的理论模型和基组进行单分子与晶胞多分子模拟,获得它们的THz理论吸收光谱。对比理论与实验光谱,借助GaussView3.09软件的视频功能,对它们的振动模式进行探讨,发现THz吸收峰主要是由分子内的集体振动模式造成的。随着频率升高,分子的刚性振转模式减弱,而分子内部基团振转模式加强。本论文的另一部分工作是选取菠菜的提取物三种植物光合膜蛋白,利用THz-TDS技术测量微量样品的THz光谱响应,设计适合该微量样品的THz测量方法,利用THz技术测试生物大分子的光谱响应,进一步探究分子内部的结构差异。本研究不仅为氨基酸及蛋白质分子的应用研究提供借鉴,而且为以后生物大分子的微量测试研究提供了参考。更多还原

【Abstract】 Terahertz (THz) wave,which lies between infrared and microwave in electromagnetic spectrum,belongs to far-infrared band. In the last decade, rapid progress in ultra-fast laser technology provides a steady and reliable optical source for the THz pulses generation,which greatly promotes the research in the THz waveband that is difficult to access before.THz time-domain spectroscopy (THz-TDS), as a newly technique of THz technology, has been widely used in the sensing and imaging field. THz radiation has low photon energies and will not cause harmful photo-ionization in biological tissues. Owing to these advantages, THz-TDS technology is a hot topic for nondestructive sensing in the bio-related fields. Until now this technique has made many significant experimental results in some bio-molecules; the spectrum analysis study in THz range, however, develops incomplete relative to the experiment. Researching adaptive simulation software and methods will help to understand logically the origin of THz spectrum.The main work of this paper is that,we obtained the THz spectra of five amino acids,such as L-methionine and L- threonine ,ascribed and discussed their absorption spectra with experiment and theory simulation.We Obtained their reliable spectra in 0.2-2.8THz by THz-TDS technology. the moleculer structures were download from cambridge structural database ,choose different theories and basis sets such as DFTof Gaussian03,using single and polymolecular conformation to simulate,compare the calculated results and experiment,then with the help of Gaussian View 3.09,we discuss their far-infrared collective vibrational modes. It was found that the absorption peaks are mainly caused by different intramolecular collective vibrational mode,as the frequency higher,the rigidity collective vibrational mode weaker,the group moveing in molecules strengthen.The other work is we select three chlorophyll protein extract from spinach,measure spectrum respond of minim sample with THz-TDS technology. And explore the difference in molecules.This study not only offer references to the application of amino acids and protein,but also useful for mini sample measurement.更多还原