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Pulsed-laser excited photothermal study of glasses and nanoliter cylindrical sample cell based on thermal lens spectroscopy.

机译：基于热透镜光谱的玻璃和纳升圆柱样品池的脉冲激光激发光热研究。

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摘要

The research in this dissertation presents Pulsed-Laser Excited photothermal studies of optical glasses and cylindrical sample cell.;First, a study of a photothermal lens experiment and the finite element analysis modeling for commercial colored glass filters is done. The ideal situation of a semiinfinite cylinder approximate model used to describe the photothermal lens experiment requires the boundary condition that there is no transfer of heat from the glass to surrounding when the glass is excited with a laser. The finite element analysis modeling for photothermal signal with coupling heat with surrounding shows the thermal heat transfer between the glass surface and the coupling fluid. This work shows that the problem can be resolved by using pulsed laser excitation where the signal decay is faster than the heat diffusion to the surrounding, and finite element analysis modeling to correct the likely deviation from semi-infinite cylinder approximate models.;Second, finite element analysis modeling of a photothermal lens signal also shows that there are slow and fast components of signals, which are detected by using a fast response detector and is explained to be due to the axial and radial transfer of heat. A semi-analytical theoretical description of the mode-mismatched continuous and pulsedlaser excitation thermal lens effect that accounts for heat coupling both within the sample and out to the surrounding is presented. The results are compared with the finite element analysis solution and found to be an excellent agreement. The analytical model is then used to quantify the effect of the heat transfer from the sample surface to the air coupling fluid on the thermal lens signal. The results showed that the air signal contribution to the total photothermal lens signal is significant in many cases.;Third, surface deformation phenomena are quite common when glasses are excited by laser. Finite element analysis modeling of a surface deformation phenomenon is done. A thermal lens reflection experiment is carried out and results are compared with modeling. The effect of coupling fluid on sample is taken in to account to make more accurate measurement of thermophysical properties of solid sample.;Fourth, a novel apparatus for performing photothermal lens spectroscopy is described which uses a low-volume cylindrical sample cell with a pulsed excitation laser. Finite element analysis modeling is used to examine the temperature profile and the photothermal signal. The result of finite element analysis is compared with the experimental result. The experimental photothermal lens enhancement has been found to be that predicted from theory within experimental error.
机译：本文对光学玻璃和圆柱状样品池的脉冲激光激发光热进行了研究。用于描述光热透镜实验的半无限柱面近似模型的理想情况需要边界条件，即当用激光激发玻璃时，热量不会从玻璃传递到周围。具有耦合热与周围环境的光热信号的有限元分析模型显示了玻璃表面和耦合流体之间的热传递。这项工作表明，可以通过使用脉冲激光激发（信号衰减比热量向周围的扩散快）来解决该问题，并使用有限元分析模型来校正与半无限圆柱近似模型的可能偏差。光热透镜信号的元素分析模型还显示，存在信号的慢速分量和快速分量，这些分量通过使用快速响应检测器检测到，并解释为归因于轴向和径向的热传递。提出了模式不匹配的连续和脉冲激光激发热透镜效应的半分析理论描述，该效应说明了样品内部以及外部与周围环境之间的热耦合。将结果与有限元分析解决方案进行比较，发现结果非常吻合。然后，将分析模型用于量化从样品表面到空气耦合流体的热传递对热透镜信号的影响。结果表明，在许多情况下，空气信号对总的光热透镜信号的贡献很大。第三，当激光激发玻璃时，表面变形现象非常普遍。完成了表面变形现象的有限元分析建模。进行了热透镜反射实验，并将结果与​​建模进行了比较。考虑到耦合流体对样品的影响，以便更精确地测量固体样品的热物理性质。第四，描述了一种用于执行光热透镜光谱的新型设备，该设备使用带有脉冲激发的小体积圆柱形样品池激光。有限元分析建模用于检查温​​度曲线和光热信号。将有限元分析的结果与实验结果进行比较。已经发现实验光热透镜的增强是根据理论在实验误差范围内预测的。

著录项

  • 作者

    Joshi, Prakash Raj.;

  • 作者单位

    Utah State University.;

  • 授予单位 Utah State University.;
  • 学科 Chemistry Analytical.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 176 p.
  • 总页数 176
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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