3-DIMENSIONAL THERMAL-CONDUCTIVITY-TENSOR MEASUREMENT OF A POLYMER CRYSTAL BY PHOTOTHERMAL PROBE-BEAM DEFLECTION

Using Fourier transforms we have calculated the solutions of the three -dimensional (3D) thermal-conduction equation in an anisotropic medium . The temperature distribution at the surface of the sample and a 3D t hermal-conductivity tensor is measured by the photothermal-probe-beam- deflection technique. We show that the expression for the deflection a ngle can be the same as in an isotropic medium, provided that an effec tive thermal conductivity relative to the polymeric-chain axis and a r escaled sample thickness are considered. This theoretical model is fou nd to be in good agreement with the experimental data for an orthorhom bic polydiacetylene sample (4BCMU).