Abstract
We propose the thermal-mode spectroscopy (TMS), a new experimental technique for thermal conductivity of minute specimen. The TMS method is based on the excitation and detection of "thermal modes" using an optical pump-probe technique. All existing methods are based on "heat transport", and they are unsuitable for minute and high-heat-diffusivity specimens because of many ambiguous parameters. Thermal conduction is recognized as "overdamping" phenomenon of thermal wave, and it is characterized by the temperature relaxation time (corresponding to eigenvalue), which is a function of dimensions and thermal diffusivity of the specimen. By solving the eigenvalue problem of heat equation, we theoretically obtain the relaxation time and then the thermal conductivity. Because the TMS method needs no ambiguous parameters owing to the eigenvalue method and the non-contact measurement, we can determine thermal conductivity more accurately than other previous methods.
