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以太赫兹时域光谱(THz-TDS)系统为手段,以常见农药氟氯氰菊酯为研究对象,探讨了利用液体农药在太赫兹波段的光谱特征对其进行定量检测的方法.选择正己烷作为基底溶液,配制了浓度为1~10μg/m L的样品溶液,选取0.5~1.5 THz波段计算样品溶液的平均吸收系数,并基于朗伯比尔定律采用最小二乘法得到了样品溶液中氟氯氰菊酯浓度与其平均吸收系数的线性关系,从而实现利用THz-TDS定量检测氟氯氰菊酯浓度的目的.研究表明,分辨力可以达到0.25μg/m L.对0.20μg/m L的样品溶液进行定量分析,结果误差为1%,验证了本文方法的有效性.采用人工神经网络(ANN)对检测方法进行非线性优化,建立了一个简单的BP神经网络模型,结果表明,该方法能够检测出浓度为0.20μg/m L的氟氯氰菊酯溶液,满足国家标准检测要求.
In this paper, THz-TDS system is taken as a measure to investigate the spectroscopic characteristics of liquid pesticides in the terahertz wave band, using common cyhalothrin as the research object.Selecting n-hexane as the base solution, The sample solution with the concentration of 1 ~ 10μg / m L was prepared, the average absorption coefficient of the sample solution was calculated by 0.5 ~ 1.5 THz band and the average absorption coefficient of cyhalothrin in the sample solution was obtained by the least square method based on Lambert’s law The linear relationship between the concentration of cyfluthrin and THz-TDS was achieved.The results showed that the resolution could reach 0.25μg / m L. Quantitative analysis of 0.20μg / m L sample solution showed that the error was 1% The validity of the method proposed in this paper is validated.The artificial neural network (ANN) is used to optimize the detection method and a simple BP neural network model is established. The results show that this method can detect fluorine with a concentration of 0.20μg / m L Cypermethrin solution to meet the national standard testing requirements.