为了分析叶绿素分子在太赫兹频段的吸收特性,也为探索生物样品的鉴定以及混合物成分测定的新方法,采用傅里叶变换红外光谱仪(FTIR)和密度泛函理论(density functional theory,DFT)研究了马尾松松针叶绿素以及叶绿素a和b标准样的太赫兹光谱。结果表明,萃取的马尾松松针叶绿素以及叶绿素a和b标准样在2.86 THz频段均出现包络吸收峰。借助于密度泛函理论,计算了单分子叶绿素a和b的太赫兹光谱,计算结果表明叶绿素a在2.86 THz频段的包络吸收峰由叶绿素分子内的卟啉环和叶绿醇的振动和转动产生。由于理论计算采用单分子结构,与实验采用的叶绿素晶体结构存在差别,导致计算的叶绿素b分子虽然在2.86 THz频段有吸收峰,但是未呈现包络吸收特性,这表明除了分子内的相互作用力,分子间的弱相互作用力产生的振动和转动对于叶绿素b的太赫兹光谱吸收特性同样有重要的影响。
Abstract
This paper presents the investigation of the THz spectra of chlorophyll of masson pine leaf, chlorophyll a and b standard sample by using Fourier transform infrared spectroscopy(FTIR)and density functional theory(DFT), in order to study the vibration and rotation of chemical bonds in chlorophyll molecule at THz frequencies, which will be used to identify the components in mixing biological samples. The frequency shift characteristic of THz spectra of chlorophyll due to the change of molecular structure will efficiently detect the development of pine wilt disease. The THz spectra of the extracted chlorophyll of masson pine leaf display a strong absorption at 2.86 THz, and weak absorption at the same frequency occurs for chlorophyll a standard sample, and chlorophyll b standard sample, which originates from porphyrin ring and phytol in the chlorophyll structure. In the other frequencies, the absorptions were not distinct. Based on the absorption performance of chlorophyll, we can identify the mixing biological samples. We studied the theoretical mechanism of absorption frequencies for chlorophyll by terms of DFT. The calculated results indicate the vibration and rotation originated from intermolecular interactions have more important effect on the THz absorption spectra compared with intramolecular interactions.
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基金
收稿日期:2014-10-08 修回日期:2014-12-09
基金项目:国家自然科学基金项目(31200541,31170668); 江苏省自然科学基金项目(BK2012417); 江苏高校优势学科建设工程资助项目(PAPD)
第一作者:蒋玲,博士。*通信作者:刘云飞,教授。E-mail: lyf@njfu.edu.cn。
引文格式:蒋玲,虞江萍,徐雨田,等. 叶绿素的太赫兹光谱特性[J]. 南京林业大学学报:自然科学版,2015,39(6):181-184.
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