近红外光谱涵盖了有机分子中C—H, N—H和O—H等含氢基团的倍频和合频产生的光谱, 提供了分子的结构、 组成、 状态等信息, 是研究有机物含氢基团振动的重要方法, 常用于食品、 农作物等的定性定量分析。 生化领域内所研究对象也都含有氢基团, 这些含氢基团吸收频率特征性强, 受分子内外环境影响小, 近红外光谱特性更稳定, 故可用于化学战剂和危险化学品检测。 沙林是一种神经性化学毒剂, 研究其结构、 化学特性及光谱性质时, 为保证安全, 实验中常用模拟剂样品代替测试, 但目前尚无公允的沙林毒剂近红外模拟剂。 采用密度泛函理论(DFT), 基于Gaussian程序包, 利用B3LYP/def2-SVP对沙林分子进行基态结构优化, 计算了沙林分子的精细结构和分子基频振动模式, 引入广义二阶微扰理论(GVPT2)建立了模拟生化毒剂近红外光谱的理论模型, 得到近红外振动峰与主要振动模式, 由倍频(Overtones)和合频(Combination Bands)振动绘制得到近红外光谱。 对沙林在近红外区域内的含氢基团进行解析, 对其特征峰进行指认, 得到沙林分子在1 150、 1 362和1 500 nm处的三个特征峰及其振动模式, 其中1 150 nm峰是由多个倍频和合频的组合振动贡献产生; 1 362 nm是一个较宽的吸收振动峰, 主要由分子中与C原子相连的原子合频和其他的非C, H原子产生的倍频或合频引起的; 1 500 nm位置的近红外振动峰主要由C8相关的振动模式贡献产生。 通过密度泛函理论建立沙林的近红外光谱理论模型, 通过实验验证了其理论模型的可行性, 为寻找其近红外光谱模拟剂提供理论支撑。

Near-infrared spectroscopy is mainly the overtones and combination bands absorption spectra of organic molecules, which are generated by the overtones and combination bands of hydrogen-containing groups such as C—H, N—H, O—H, etc., which can obtain molecular structure, composition, state and other information. This technology is an important method for studying the vibration information of hydrogen-containing groups in organic matter and is often used for qualitative and quantitative analysis of biological substances such as food and crops. The research objects in the biochemical field also have hydrogen-containing groups. These hydrogen-containing groups have strong absorption frequency characteristics, are less affected by the internal and external environment of the molecule, and have more stable spectral characteristics in the near-infrared spectrum. This technology can be used to detect chemical warfare agents and hazardous chemicals. Sarin is a neurotoxic chemical agent. When studying its structure, chemical properties and spectral properties, in order to ensure safety, simulants are often used in the experiment to substitute for testing, but there is no fair near-infrared simulant for sarin. This paper uses density functional theory (DFT), based on the Gaussian program package, and uses B3LYP/def2-SVP to optimize the ground state structure of the sarin molecule, and calculates the fine structure of the sarin molecule and the fundamental frequency vibration mode of the molecule. The generalized second-order perturbation theory (GVPT2) is introduced to establish a theoretical model for simulating the near-infrared spectrum of biochemical poisons, obtaining the near-infrared vibration peaks and main vibration modes, and the near-infrared spectrum drawn from the vibrations of overtones and combination bands. Analyze the hydrogen-containing groups of sarin in the near-infrared region, use this method to identify its characteristic peaks, obtain three characteristic peaks of sarin molecules at 1 150, 1 362 and 1 500 nm and analyze their vibration modes. Among them, the position at 1 150 nm is produced by the contribution of multiple overtones and combination bands vibration. 1 362 nm is a wide absorption vibration region, mainly caused by the combination bands of atoms connected to C atoms in the molecule and other non-C, H atoms. The near-infrared vibration peak at 1 500 nm is mainly caused by the C8 Related vibration mode contribution. In this paper, the theoretical model of Sarin’s near-infrared spectroscopy is established through density functional theory, and the feasibility of the theoretical model is verified through experiments, which provides theoretical support for finding its near-infrared spectroscopy simulation agent.