Professor Justin Wark

Abstract:

Although the realisation of femtosecond X-ray free electron laser (FEL) X-ray pulses is still some time away, X-ray diffraction experiments within the sub-picosecond domain are already being performed using both synchrotron and laser-plasma based X-ray sources. Within this paper we summarise the current status of some of these experiments which, to date, have mainly concentrated on observing non-thermal melt and coherent phonons in laser-irradiated semiconductors. Furthermore, with the advent of FEL sources, X-ray pulse lengths may soon be sufficiently short that the finite response time of monochromators may themselves place fundamental limits on achievable temporal resolution. A brief review of time-dependent X-ray diffraction relevant to such effects is presented.