Photothermal phenomenon: Extended ideas for thermophysical properties characterization

Abstract

The photothermal phenomenon involves material photon heating in the form of continuous waves, modulated waves, or pulses. The resulting temperature rise carries very rich information about the material's structures and thermophysical properties. This review is constructed to cover some of the extended ideas of the photothermal phenomenon for measuring a material's thermophysical properties and interface thermal conductance/resistance. For frequency-domain photothermal phenomena, the photoacoustic (PA) and photothermal radiation (PT) techniques provide great ways to measure coatings and suspended samples, which can also be measured using the laser flash and time-domain thermoreflectance (TDTR) techniques. Thermal probing based on electrical thermal sensing is successfully implemented in the transient photo-electro-thermal (TPET) and pulsed laser-assisted thermal relaxation (PLTR) techniques, which significantly extend the capability of laser flash technique to micro/nanoscale 1D structures. The energy transport state-resolved Raman (ET-Raman) is distinct from traditional techniques in its material-specific thermal sensing capability and integral way of ultrafast thermal sensing. Detailed physics discussions are provided for all these techniques, including their advantages and limitations. Still, large development rooms exist for the relatively new techniques, including TPET, PLTR, and ET-Raman. These include measurements under extreme situations, sensitivity improvement, and distinguishing conjugated physical processes.