Observation of Heat Diffusion across Submicrometer Metal Thin Films Using a Picosecond Thermoreflectance Technique

摘要

We have observed heat diffusion across submicrometer metal thin films for the first time using a picosecond thermore- flectance method. The boundary between a film and a transparent substrate is heated by a picosecond laser pulse. Heat generated by the pump laser pulse diffuses towards the front surface of the thin film. The temperature change on the front surface opposite to the heated area is probed by the reflectivity of another picosecond laser pulse.