Femtosecond laser induced structural dynamics and melting of Cu (111) single crystal: An ultrafast time-resolved x-ray diffraction study.


Femtosecond 8.04 keV X-ray pulses are used to probe the lattice dynamics of 150 nm Cu (111) single crystal on a mica substrate irradiated with 400 nm, 100 fs laser pulses. At pump fluence below the damage and melting threshold, we observed lattice contraction due to the formation of a blast force and coherent acoustic phonons with a period of ~69 ps. At larger pump fluence, solid to liquid phase transition, annealing, and recrystallization were measured in real time by monitoring the intensity evolution of the probing fs x-ray rocking curves and their agreement with theoretical simulation results. The experimental data suggests the melting process is a purely thermal phase transition. This study provides, in real time, an ultrafast time-resolved detailed description of the significant processes that occur as a result the interaction of a femtosecond light pulse with the Cu (111) crystal surface.

Journal of Applied Physics, Vol. 121, 055102