大气开放光路傅里叶变换红外光谱的定性分析

Qualitative Analysis of Open-Path Fourier Transform Spectra

通过目标波段熵最小化(BTEM)和目标因子分析(TFA)两种化学计量学方法研究了大气开放光路傅里叶变换红外(OP/FT-IR)光谱,从多组分测量数据重建特定目标分子的光谱特征,以实现对大气这种复杂体系的定性分析。在牧场周围完成了5次连续OP/FT-IR光谱测量,将光谱按照测量时间顺序排列,获得5个数据矩阵作为研究对象。结果表明,BTEM和TFA两种方法均可从多组分光谱数据矩阵重建出目标分子的光谱特征,重建效果略有差异。TFA能够克服干扰,提取出目标分子的光谱特征,其重建光谱与相应的参考光谱高度相似。BTEM方法无需目标分子的参考光谱,目标函数最优解所对应的谱图就是纯组分光谱。本研究利用两种方法各自的优势,用化学计量学方法定性分析OP/FT-IR光谱,不仅将BTEM方法应用于OP/FT-IR光谱,而且比较这两种方法的应用,为实现多组分OP/FT-IR光谱定性分析提供了新思路。

Open-path Fourier transform infrared （ OP/FT-IR） spectra were analyzed with target factor analysis （ TFA） and band-target entropy minimization （ BTEM） respectively, with the purpose to reconstruct spectral characteristics of target molecules from matrices of spectra. Five sessions of continuous OP/FT-IR monitoring were carried out around farms. For each session, the spectra were arranged row-wisely in order of measuring time, which yielded five matrices for data analysis. Results showed that both BTEM and TFA could reconstruct spectral characteristics of target molecules from the spectral data matrix, but the performance of the two methods differed slightly. TFA can retrieve spectral features of target molecules in the presence of interferences, and the reconstructed spectra are similar to corresponding reference. BTEM can implement such spectral retrieval without the reference spectrum. This work presents not only the application of BTEM method to qualitative analysis for OP/FT-IR spectra, but also a thorough comparison between the two methods. The conclusion is helpful to qualitative analysis of complex multi-component systems.