路易氏剂红外吸收截面积的测定与光谱模拟

采用长程傅里叶红外光谱仪在600～1 600 cm-1波段内对不同浓度路易氏剂-1的气相红外透射光谱进行了测量，其特征频率为814，930，1 563 cm-1;并运用比尔-朗伯定律计算了对应特征频率的红外吸收截面积σ值，依次为3.89±0.01, 1.43±0.06, 4.47±0.05(×10-20 cm2·molecule-1)。路易氏剂-1测量光谱在1 158和1 288 cm-1处也有微弱的吸收峰。利用Gaussian09软件包中的密度泛函理论对系列路易氏剂的红外光谱进行理论模拟，其稳定构型和振动频率在b3lyp/6-311+g(d,p)水平上计算。并利用可视化软件Gaussview5.08对各频率的振动模式进行归属。理论计算的红外光谱和实测光谱在600～1 600 cm-1波段内非常吻合，特征频率的相关系数为0.999 1。计算光谱还发现了0～600 cm-1波段内与砷原子有关的振动频率，为293，360和374 cm-1。用最小二乘法处理试验和计算结果中的特征频率，得到了适合路易氏剂-1的红外光谱频率矫正因子为0.977。利用该矫正因子对路易氏剂-1，路易氏剂-2，路易氏剂-3的红外光谱计算频率进行矫正。结果表明获得的路易氏剂理论红外吸收光谱可为该系列化合物的结构性质预测和远程红外光谱监测等提供参考。

Measurements of IR Absorption Across Section and Spectrum Simulation of Lewisite

The vapor infrared transmission spectra of varied concentration of lewisite-1 were measured by a long-path FT-IR spectrometer, and its characteristic frequencies are 814, 930, 1 563 cm-1; their infrared absorption cross section (σ) were determined using Beer-Lambert law. The corresponding σ values are 3.89±0.01, 1.43±0.06, 4.47±0.05(×10-20 cm2·molecule-1). Two little teeny peaks, 1 158, 1 288 cm-1 were found in the measured spectra. Density Functional Theory (DFT) was applied to calculated the infrared spectra of lewisite-1, -2, -3 on a b3lyp/6-311+g(d,p) level by Gauss09 package. The vibration modes were assigned by Gaussview5.08. The calculated spectra and experimental spectra are in good agreement with each other in 600～1 600 cm-1 range, for the Person’s r is 0.999 1. The calculated spectra also showed three characteristic frequencies (293, 360, 374 cm-1) related to As atom. 0.977 was a scaling factor we determined for lewisite-1 through least-square error and its performance to scale lewisite-1, -2, -3 was acceptable. The results of this work are useful for monitoring environmental atmospheric concentrations of lewisite.