The XPP/KMC-3 is a hard x-ray beamline dedicated to time-resolved x-ray diffraction and absorption spectroscopy experiments (EXAFS, XANES). It is equipped with an x-ray mirror assembly and a double monochromator, which can be removed from the x-ray beam path to allow for experiments with a monochromatic or a white x-ray beam. The energy range extends from 2 keV to 14 keV. In addition, the beamline comprises an ultrafast laser as a pump source for time-resolved experiments. In the near furture, a four-circle diffractometer setup in a vacuum chamber will allow for sample cooling down to 30°K.
Typical applications of the beamline are:
Currently the beamline is only equipped for time-resolved x-ray diffraction experiments. If you wish to submit a proposal please contact the beamline scientist in advance to discuss the feasibility of your experiment.
Layout-plan of the XPP/KMC-3 Beamline
Our laser in the Optics Hutch is a multi-stage Yt-doped oscillator - amplifier system (Impulse, Clark-MXR). It is synchronized to the RF-signal of the storage ring with an accuracy better than 5 ps. The main laser parameters are:
For time-resolved experiments, the laser is coupled to the experimental hutch via a chicane. The optics hutch provides several nonlinear wavelentgh conversion setups, e.g., NOPA, SHG and DFG.
Cryo-EXAFS station at beamline KMC-3. The station is currently in the last stages of development and will accept external proposals for 2016/II.
For details and current status of the experimental station contact the station manager Dr. Götz Schuck.
"The X-ray Pump-Probe (XPP) experimental station predominantly aims at investigating hard and soft matter under a broad range of ambient conditions using time-resolved X-ray diffraction." http://dx.doi.org/10.17815/jlsrf-2-82
For details and current status of the experimental station contact the station scientist.
The XPP endstation is designed for time-resolved pump -- X-ray probe experiments. We use optical laser excitation or electrical excitation schemes and study the structural non-equilibrium response of a sample. Therefore we routinely use a gated area detector that is synchronized to the single bunch of the BESSY filling pattern, that is, we record data only when a short burst of X-ray photons arrive at the sample. With this scheme we are essentially only limited by the length of the X-ray pulses, which is around 80 ps in standard hybrid mode and 15 ps in low-alpha operation mode. Using a home-built fast scintillation detector (Scionix) with a commercial photomultiplier tube (Hamamatsu), we are able to obtain 4 ns time resolution in time-correlated photon counting mode and are able to measure simulateneously delays up to 33 μs during one sample scan. Static experiments can be performed using a CyberStar detector.
For the optical sample excitation, we use a synchronized laser system (Light Conversion Pharos) that is synchronized with a Menlo RRE-Syncro module to the bunch timing of BESSY. With an electronic delay unit we can remotely shift the arrival time of the laser pulses with respect to the X-ray pulses up to 1 ms, which is limited by the repetition rate of the laser with a time resolution of roughly 1 ps.
A special setup for the investigation of ferroelectric switching dynamics is available upon request. We use a Keithley 3390 Arbitrary Function Generator, either in stand-alone mode or synchronized to the BESSY ring, to apply electric field pulse sequences to the sample with a tungsten needle. A voltage amplifier is available that allows to multiply the output of the function generator by a factor of 5.
We offer a high-vacuum environment (10-6 mbar) for the sample. The sample is mounted on a 4 circle goniometer (3 circle goniometer in vacuum) and the detectors mounted outside on the 2Θ arm. The sample temperature can be varied between 10 and 400 K using a closed-cycle cryostat.