Time-resolved X-ray diffraction from laser-heated crystals

We present first results in an ongoing investigation aimed at observing xray radiation from a synchrotron with sub-ps time-resolution. We aim to implement a switch based on ultra-short pulse laser heating of diffraction crystals. In these first experiments performed with a q-switched Nd:YAG laser, the temporal resolution of the experiment is 15 ns limited by the response time of our detector. We find a change in diffracted intensity, due to thermal expansion of the crystal over an x-ray absorption depth. The reduction in diffracted intensity is limited by the laser fluence to about 15%. We also show theoretical results based on the solution of the time-resolved dynamic diffraction equations for the case of x-ray diffraction from a crystal heated with a sub-ps laser pulse. Results for both Si and InP are discussed, and we propose InP as a good crystal for future experiments.