Transient Thermoreflectance Investigation of Damping from Vibrating Dislocations in Oscillating Metal Films

Transient thermoreflectance (TTR) signal generated from pulse laser-induced oscillation of delaminated metal films of Al, W, and In is determined and the acoustic contribution due to strain is evaluated. The decay in the amplitude of the acoustic oscillations is modeled in terms of Granato–Lṻcke theory of vibrating dislocations with mobility restricted under drag exerted by electron scattering. The values of the relative energy loss factor from the experimental observations and from dislocation modeling are shown to correlate well using the expected dislocation density in annealed metal foils.