付里叶变换近红外漫反射光谱分析应用基础的研究

STUDIES ON THE THEORETIC BASES OF APPLIED FTNIRDRSA

本文讨论了NIRDRSA法,该分析是建立在漫反射光谱参数(反射吸光度或KubelkaMunk函数)的线性与加合性基础上。用数学分析和实验验证的方法研究了线性和加合性,样品的近红外反射率R与样品的化学组成存在非线性的关系。当散射系数为常数时,反射吸光度A(A=-logR)和化学组成存在近似线性关系。为了改善线性,可用反射吸光度的一次微分和二次微分光谱。因此样品中任一组份的含量可以用某一多元线性函数来计算。样品的制备技术、颗粒的大小、样品层的厚度、密度可影响散射系数,因此NIRDRSA必须保持制样条件的一致。本研究还说明付里叶变换光谱仪非常适合于NIRDRSA。

The theoretic bases of applied NIRDRSA are discussed.It is based upon both li- nearity and additivity of spectroscopic parameters(i.e.reflective absorbance and Kubelka-Munk function).In this Paper the linearity and additivity of NIRDRSA parameters are studied by using mathematical analysis and experiment.In these studies we found that,although the sample compo- nents is related to the NIR reflectance(R)in a nonlinear way but it's relation to the reflective ab- sorbanee A(=log 1/R)in a near linear way.The linearty can be further improved by using the d(log(1/R))and d^2(log(1/R))instead of A.On the foundation of these studies,the con- tents of every composition in a multicomponcnt sample may be calculated by a multiviariate linea- ry equation.We also found it is necessary to keep the scattering coefficient constant in NIRDRSA. Deviation may arise in sample preparation,such as grinding techniques,thickness of samples,size of particles,density and homogenit of samples.So condition of sampling must be optimized and standarized to obtain the best results.It is found that fourier transform spectrophotometr is very fit for NIRDRSA.