Equipment

    Transient grating (TG) spectroscopy is a pump–probe technique that measures in-plane thermal diffusivity by monitoring the spatially periodic temperature grating induced by interfering laser beams at the sample surface.

    By varying the grating period, TG probes length-scale-dependent heat conduction, enabling mean-free-path spectroscopy to provide insight into the mean-free-path distribution of heat carrying phonons. 

    We use TG to investigate the influence of molecular alignment on thermal transport in polymers and  characterize in-plane thermal transport in transition metal dichalcogenides, organic frameworks, and perovskites to elucidate the underlying mechanisms of heat conduction. 

    Time-domain thermoreflectance (TDTR) is an optical pump-probe method that measures thermal properties of thin films by measuring the change in thermo-reflectance induced by the pump on the sample surface.

    Specifically, it confines the temperature rise to near-surface regions from tens of nanometres to several micrometres, and this localized heating enables precise measurement of the thermal properties of thin films and material interfaces.

    We measure the thermal properties of advanced electronic materials, including ultra-wide-bandgap semiconductors for power electronics and ferroelectrics for next-generation memory.

    Scanning ultrafast electron microscopy (SUEM) is an imaging technique that visualizes photoexcited carrier dynamics with the nanometer spatial resolution of scanning electron microscopes and the sub-picosecond temporal resolution of ultrafast lasers.

    By detecting photoinduced changes in secondary electron emission, SUEM acquires time-resolved SEM images of the sample surface.

    Our laboratory uses SUEM to investigate photoexcited carrier dynamics in advanced energy materials, providing insight into microscopic processes that govern energy conversion and transport.