LAUSR

This work presents measurements of laser-induced solid-solid phase transitions in Co nanoparticles, using time-resolved wide-angle x-ray scattering with < 100-ps time resolution. A comparison of the experimental results with scattering simulations indicates a phase transition from the as-synthesized (cid:2) phase into a mixed phase of 2 / 3 hcp and 1 / 3 fcc character during the first 100 ps. The measured scattering signal observed at the shortest investigated time delay of 20 ps has less scattering intensity at the dominant fcc / hcp Bragg peak positions compared to the difference signal acquired at 100 ps. This suggests the formation of a partially disordered solid intermediate phase on the sub-100-ps timescale.