Thermal diffusivity measurements in liquids using signal common-mode-rejection demodulation in a thermal-wave cavity

A recently developed signal common-mode rejection demodulation signal metho dology [Mandelis , Rev. Sci. Instrum. 71, 2440 (2000)] has been used to mak e direct absolute thermal diffusivity measurements in liquids using a therm al-wave cavity. This methodology combines the precision of the thermal-wave cavity scan and the flexibility of modulation-frequency scan modes, along with baseline suppression, yielding a high-resolution technique for thermal diffusivity measurements in liquids. The thermal diffusivity of two pure l iquids (distilled water and ethylene glycol) has been measured and good agr eement has been obtained with values reported in the literature. (C) 2001 A merican Institute of Physics.