非均匀介质的光学和红外光谱性质

【作者】 宋宁；

【导师】 俞钢； 徐晓轩；

【作者基本信息】 南开大学 ， 光子学与光子技术， 2009， 博士

【摘要】 自然界中存在的原生态介质绝大多数都是非均匀介质,同时非均匀介质也包括人工合成的各种复合材料、多晶材料以及纳米材料等等。光在这些非均匀介质中的传播行为主要表现为非均匀介质对光的散射和吸收,因而非均匀介质的光学特性以及光在介质中传播的散射理论则是人们一直研究的重要内容,这对于很多领域都有着重要的理论意义和实际应用价值。本论文基于流理论的散射模型,将非均匀介质的光学和光谱性质的研究概括为两大类问题:一类是正问题,一类是反问题。通过流理论对介质的光学参数进行反演计算,并以含烃岩屑这种原生态非均匀材料为研究对象进行定性、定量分析,并且利用红外显微成像光谱技术在微观尺度内对含油岩石薄片进行光谱成像研究。主要内容包括:1、以非均匀介质的光散射理论为基础,对二流、修正的二流理论进行了研究,并且分别对两个理论的正问题和反问题进行了阐述。在MATLAB平台上实现了修正的二流理论对粉末样品散射系数和吸收系数反问题的计算;分析了红外漫反射光谱技术的特点、形成的物理机制,并且对漫反射光谱技术应用于定量分析中的理论基础和参数正确选择进行了深入研究。2、对含油岩屑进行了红外漫反射光谱的测量,在对生烃潜量进行定量分析时,分析了Ganz的A因子一元分析方法的局限性。本论文阐述了采用的多元分析方法的优点,论证了我们选用2800cm^-1—3100cm^-1波段进行定量分析的理论依据并且运用多元分析方法建立了稳定、准确的定量分析模型。3、散射一直被认为是红外漫反射光谱定量分析时的干扰信息,颗粒度等几何参数是决定散射光强弱的因素,所以在定量分析时要选择合适的粒度,这样才能得到理想的分析模型。虽然可以消极的利用化学计量学的方法有效地消除散射的干扰,但是我们也可以积极的利用DWT（离散小波变换）的方法在光谱中提取表征散射的低频信息,本论文用这部分低频信息建立了非常好的颗粒度的线性回归模型,对粉末样品粒度进行准确的分析,这在制药、水泥等行业有着广泛的应用前景。4、阐述了光谱成像的基本原理及其发展,并且应用显微红外成像光谱技术对含油迹的岩石薄片进行了详细的研究,对其不同化学组分的空间分布进行成像研究,在实验方法上分别采用了红外显微ATR法和显微透射实验法。在对含油岩石薄片显微成像光谱的图像处理中首次引入了图像融合技术,使得成像结果同时兼备了高光谱分辨率和高空间分辨率的双重优点。更多还原

【Abstract】 In nature, most of the primitive mediums are inhomogeneous materials. Moreover, some artificial mediums are also inhomogeneous such as synthetic, polycrystalline, nanostructured materials, etc. The light scattering theories and the optical properties of inhomogeneous materials are significant because light will be scattered or absorbed when spreading in inhomogeneous materials, which makes them valuable for the research and applications in geology, astronomy, chemistry, engineering and other fields.This thesis, based on the scattering theory, synthesizes the optical and spectral properties of inhomogeneous materials into two methods, one is forward method and the other is reverse method. We research the powders of hydrocarbon source rocks, which are primitive materials, quantitatively and qualitatively, and analyze the thin section of oiled rocks in micro scale with micro-infrared imaging spectrum technique. The main contents are as follows.1. Research two-flux and modified two-flux theory and discuss the forward method and the inverse method for two theories respectively. Compute the scattering coefficient and the absorption coefficient of the powder samples using the reverse method of modified two-flux theory by MATLAB, analyze the formative physical mechanism and characteristics of infrared diffuse reflection spectrum technique, and explain the selection of parameters and the theoretic basis of quantitative analysis by diffuse reflection spectrum.2. Measure the infrared diffuse reflection spectrums of powders of hydrocarbon source rocks by FT IR spectrometer. Quantitatively analyze the hydrocarbon generating potential. Discuss the principle and limitations of Ganz’s A factor and advantage of the multivariate analysis. Explain the reasons selecting 2800cm^-1-3100cm^-1 wave band for quantitative analysis and build a steady, accurate quantitative analysis model with multivariate analysis.3. Scattering has always been considered as a disturbance in the quantitative analysis. Intensity of scattering is determined by geometrical parameters of materials, for instance particle size etc. In order to establish an ideal quantitative analysis model, we should choose particles in a suitable size. Disturbance of scattering can be effectively eliminated with Chemometrics. However, information of low frequency denoting scattering of the spectrums can be extracted by DWT. With this information, we can create an excellent linear regression model to accurately analyze the particle size which has important applications to pharmacy, cement and other industries.4. Expound the basic principles and the development of imaging spectrum. Analyze the thin section of oiled rocks to get the space distributions of various components, especially the minim organic material by micro-ATR and transmission method respectively with micro-infrared imaging spectrum technique. Moreover, for the first time, we applied fusion technique to imaging processing, which makes results possess high spectral resolution and spatial resolution at the same time.更多还原