J. Phys. IV France 125 (2005) 83-85
Advances in thermal wave based microscopyM. Chirtoc1, X. Filip2, J.F. Henry1, J.S. Antoniow1 and J. Pelzl3
1 Lab. Thermophysique, UTAP, Université de Reims, BP. 1039, 51687 Reims, France
2 National R & D Inst. for Isotopic and Molecular Tech., PO Box 700, 3400 Cluj-Napoca 5, Romania
3 Inst. Experimentalphysik III, Festkörperspektroskopie, Ruhr-Univ., 44801 Bochum, Germany
We analyze the dependence of ac signal obtained in scanning thermal microscopy (SThM) using a Wollaston thermal probe, on thermophysical properties of the sample. The amplitude and phase sensitivities to the specific heat c and to thermal conductivity k of the sample are computed with a finite element software, in a range of k values from 0.18 Wm-1K-1 (typical insulator, PMMA) to k=2200 Wm-1K-1 (diamond). We find that the SThM signal is sensitive only to k, to an extent that favors insulating materials. Moreover, the signal is sensitive at least to the same extent to the tip/sample thermal resistance, that reduces drastically the dynamic range. We define a crossover frequency separating two frequency ranges, isothermal and adiabatic. The model is validated by measuring temperature profiles along an upscaled wire, using a thermographic camera and lock-in image processing.
© EDP Sciences 2005