Quantitative disentanglement of coherent and incoherent laser-induced surface deformations by time-resolved x-ray reflectivity

摘要

We present time-resolved x-ray reflectivity measurements on laser excitedcoherent and incoherent surface deformations of thin metallic films. Based on akinematical diffraction model, we derive the surface amplitude from thediffracted x-ray intensity and resolve transient surface excursions withsub-Angstrom spatial precision and 70 ps temporal resolution. The novelanalysis allows for decomposition of the surface amplitude into multiplecoherent acoustic modes and a substantial contribution from incoherent phononswhich constitute the sample heating.