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Bridging the modeling-sampling gap of mid-infrared reflectance spectroscopy of small particles, films, and fibers.

机译：弥合小颗粒，薄膜和纤维的中红外反射光谱的建模采样间隙。

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The concentration dependency of the mid-infrared (MIR) absorbance of bacterial spores, obtained by reflectance micro-spectroscopy, was determined. Linear relationships (R2 ≥ 0.99) were observed between the concentrations of spores and the baseline corrected peak absorbance for the amide absorbance regions, at coverages of less than 1 monolayer. Optical constants were calculated from these measurements, differing by a factor of 2-4 less than that in the literature. To test if the origin of the reduced cross-section was an electric field effect related to the surface selection rule, polystyrene spheres' characteristics were studied using FT-IR reflection microspectroscopy; results show that absorption has a non-linear, stair-step-like dependence on particle coverage and a wavelength dependence that can be explained by electric field standing waves (EFSW) caused by the mirrored substrate.;The same effect is found to cause progressive weakening of the observed intensity as a function of increasing wavelength in sub-monolayer coverage measurements. Thus differences seen between optical properties of particles calculated using the specular-reflection method versus those calculated using traditional aerosol methods are addressed herein given these data. A simple multilayer method for estimating particle absorption coefficients is demonstrated that compares well with reported bulk polystyrene ellipsometric values. Another simple method, based on submonolayer coverage spectra, is suitable for spectral classification analysis, but only semi-quantitatively determines absorption coefficients.;An IR camera sensitized to spectral regions tuned for detection of crime-scene blood was developed. Adaption of an IR camera with a modulated light source and utilizing digital lock-in amplifier techniques permitted differentiated response due to diffuse reflection and thermal emission. Using the AC response generated by a modulated light source is advantageous over the conventional DC response via enhancing the chemical contrast in the image which enables detection of stains of interest. We also exploit a "like-detects-like" filtering approach to demonstrate a method of using a broadband thermal detector for chemical identification applications.
机译：确定了通过反射显微光谱法获得的细菌孢子的中红外（MIR）吸光度的浓度依赖性。在小于1个单层的覆盖范围内，观察到孢子浓度与酰胺吸收区的基线校正峰吸收之间的线性关系（R2≥0.99）。由这些测量值计算出光学常数，其差异小于文献中的2-4倍。为了测试减小的横截面的起源是否是与表面选择规则相关的电场效应，使用FT-IR反射光谱法研究了聚苯乙烯球体的特性。结果表明，吸收对粒子的覆盖率具有非线性，阶梯状的依赖性，而波长的依赖性可以由镜面基板引起的电场驻波（EFSW）来解释。在亚单层覆盖率测量中，观察到的强度随波长增加而减弱。因此，在给定这些数据的情况下，本文解决了使用镜面反射法计算的粒子与使用传统气溶胶法计算的粒子的光学性能之间的差异。证明了一种简单的估计颗粒吸收系数的多层方法，该方法与已报道的批量聚苯乙烯椭偏值有很好的比较。另一种基于亚单层覆盖光谱的简单方法适用于光谱分类分析，但仅能半定量确定吸收系数。;研制了一种红外光谱仪，该光谱仪对为侦察现场血液检测而调整的光谱区域敏感。将红外摄像机与调制光源相匹配，并利用数字锁定放大器技术，可实现因漫反射和热辐射而产生的差异响应。通过增强图像中的化学对比度，使用调制光源生成的AC响应优于常规DC响应，这可以检测到感兴趣的污点。我们还利用“类似检测”过滤方法来演示将宽带热检测器用于化学识别应用的方法。

著录项

  • 作者

    Brooke, Heather.;

  • 作者单位

    University of South Carolina.;

  • 授予单位 University of South Carolina.;
  • 学科 Chemistry Analytical.;Chemistry Physical.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 288 p.
  • 总页数 288
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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