Mechanism for the ablation of Si⟨111⟩ with pairs of ultrashort laser pulses

Pairs of ultrafast laser pulses are used to ablate Si < 111 >. The fluorescence from Si atoms and ions was observed to increase by an order of magnitude as the delay between the pulses was increased. From the dependence of the fluorescence enhancement on the laser fluence and the pulse delay, it is deduced that the first pulse melts the surface and that the second pulse interacts more strongly with the liquid phase. (c) 2007 American Institute of Physics.