PICOSECOND TIME-RESOLVED SURFACE-LATTICE TEMPERATURE PROBE

Picosecond reflection high-energy electron diffraction is used as a time-resolved surface-lattice temperature probe. A picosecond laser pulse is split into two beams. The first interacts with the sample. The second activates the cathode of an electron gun creating a collimated and focused electron pulse that is well synchronized with the heating laser pulse. The electron pulse is used to generate a reflection high-energy electron diffraction pattern of the sample. Since heating results in an intensity reduction of the elastically scattered electrons (Debye-Waller effect), the diffraction pattern provides information on the surface temperature as well as structure. Time-resolved measurements of the picosecond laser-heated surface show general agreement with a heat diffusion model.