Direct Measurement of the In-Plane Thermal Diffusivity of Semitransparent Thin Films by Lock-In Thermography: An Extension of the Slopes Method
Direct Measurement of the In-Plane Thermal Diffusivity of Semitransparent Thin Films by Lock-In Thermography: An Extension of the Slopes Method
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DOI：
10.1021/acs.analchem.9b01583
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发表时间：
2019-07-02
影响因子：
7.4
通讯作者：
Retsch, Markus
中科院分区：
文献类型：
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作者：
Philipp, Alexandra;Pech-May, Nelson W.;Retsch, Markus
我们提出了一种众所周知的斜率法的扩展，用于表征半透明聚合物薄膜的面内热扩散系数。我们引入了一个理论模型，该模型考虑了对流和辐射机制引起的热损失，以及材料对激发激光热源的半透明性（可见范围）和薄膜表面的多次反射。最重要的是，还考虑了材料在红外探测范围内的潜在半透明性。通过数值模拟和表面温度的渐近展开式证明了斜率法对热薄状态下的任何半透明薄膜都是有效的。在覆盖广泛吸收系数（到激发波长）的半透明聚合物薄膜上进行了面内热扩散率的测量，并验证了我们的理论发现。我们的红外相机的红外探测范围)验证了我们的理论发现。
We present an extension of the well-known slopes method for characterization of the in-plane thermal diffusivity of semitransparent polymer films. We introduce a theoretical model which considers heat losses due to convection and radiation mechanisms, as well as semitransparency of the material to the exciting laser heat source (visible range) and multiple reflections at the film surfaces. Most importantly, a potential semitransparency of the material in the IR detection range is also considered. We prove by numerical simulations and by an asymptotic expansion of the surface temperature that the slopes method is also valid for any semitransparent film in the thermally thin regime. Measurements of the in-plane thermal diffusivity performed on semitransparent polymer films covering a wide range of absorption coefficients (to the exciting wavelength and in validate our theoretical findings. the IR detection range of our IR camera) validate our theoretical findings.