Abstract
Hard X-ray free electron lasers allow for the first time to access dynamics of condensed matter samples ranging from femtoseconds to several hundred seconds. In particular, the exceptional large transverse coherence of the X-ray pulses and the high time-averaged flux promises to reach time and length scales that have not been accessible up to now with storage ring based sources. However, due to the fluctuations originating from the stochastic nature of the self-amplified spontaneous emission (SASE) process the application of well established techniques such as X-ray photon correlation spectroscopy (XPCS) is challenging. Here we demonstrate a single-shot based sequential XPCS study on a colloidal suspension with a relaxation time comparable to the SACLA free-electron laser pulse repetition rate. High quality correlation functions could be extracted without any indications for sample damage. This opens the way for systematic sequential XPCS experiments at FEL sources.
Highlights
Hard X-ray free electron lasers allow for the first time to access dynamics of condensed matter samples ranging from femtoseconds to several hundred seconds
Dynamics ranging from femtoseconds to seconds over length scales between atomic dimensions and several hundred nm can be studied by X-ray Photon Correlation Spectroscopy (XPCS)[1,2,3]
Single shot speckle patterns were taken from both a static sample consisting of PMMA spheres and a dynamic sample consisting of silica spheres dispersed in glycerol
Summary
Hard X-ray free electron lasers allow for the first time to access dynamics of condensed matter samples ranging from femtoseconds to several hundred seconds. The accessible time scale of sequential XPCS is determined by the repetition rate of the linac at FEL facilities This allows studies down to 8.3 ms at the Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory (USA) or 16.6 ms at the Spring-8 Angstrom Compact free-electron Laser SACLA (Japan)[19,20,21]. As discussed by Grübel et al.[2] the pulsed structure of the incoming beam allows thermal relaxation of the sample between two subsequent pulses This is typically not possible at storage ring sources, where the incoming flux has to be reduced in case of radiation sensitive samples. This will be of big benefit to a large class of experiments
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