持久性有机物硫丹的太赫兹光谱研究

Terahertz Time-Domain Spectroscopy of Alpha Endosulfan Persistent Organic Pollutant

以最新被斯德哥尔摩公约列入持久性有机污染物的硫丹为研究对象,采用太赫兹时域光谱技术获得了α硫丹在0.2～2THz频率范围内的吸收系数谱和折射率谱,结果显示在此频率范围内存在有一系列特征吸收峰,并且通过实验和理论计算对比发现在1.70和1.88THz处的实验吸收峰与1.68和1.91THz处的理论吸收峰有很好的吻合;经分析认为,这吻合峰是由于分子内集体振动引起的,实验中的其他峰值可能归因子分子间弱相互作用力和混合振动。研究结果证明了THz-TDS技术进行持久性有机物检测的可行性,为THz-TDS系统在持久性有机物识别和残留物检测方面的应用提供了依据。

Frequency-dependent absorption coefficient spectrum and refractive index spectrum of alpha endosulfan,a kind of persistent organic pollutants,are presented in the terahertz frequency region by terahertz（THz） time-domain spectroscopy（TDS）.The spectral features in the THz region have a number of unique characteristic absorption peaks.The result demonstrates that THz-TDS is a promising method to identify materials.Then we adopted density functional calculation method to analyze theoretic absorption coefficients of single alpha endosulfan molecule within 0.2~2 THz.The results show that absorption peaks at 1.68,1.91 THz in theoretical calculation correspond to 1.7,1.88 THz in the experiment.Finally,vibrational modes and approximate assignments were discussed,showing that these matched peaks are caused by intramolecular vibrational modes of alpha endosulfan.Others might be related to intermolecular vibrational modes or combined vibrational modes.