Characterisation of InSb non-thermal melting with femtosecond X-rays

Summary form only given. We used the technique of time-resolved X-ray diffraction with an X-ray source produced from the interaction of a 10 Hz, 120 fs, 16 mJ Ti:sapphire laser beam focused on a silicium target. The emitted 7.12 /spl Aring/ K/sub /spl alpha//, X-ray radiation is expected to last 100 fs which can give a clear mapping of the atomic motions during the phase transition. The X-ray radiation is collected by a toroidal quartz crystal and focussed onto the InSb. We used a second laser pulse from this laser system to excite the sample at fluences ranging from 200 mJ/cm/sup 2/ to 5 mJ/cm/sup 2/, which is well below the damage threshold of the semiconductor. The depth and the timescale of nonthermal process have been fully characterized.