X-Ray Pump Probe (XPP)
X-Ray Pump Probe (XPP)
The XPP instrument is dedicated to time-resolved x-ray diffraction and absorption spectroscopy experiments (EXAFS, XANES) to investigate hard and soft matter under a broad range of ambient conditions. We use optical laser excitation or electrical excitation schemes and study the structural non-equilibrium response of a sample.
depends on experiment - please discuss with Instrument Scientist
|Energy range||2 - 14 keV|
|Energy resolution||1/5000 - 1/4000|
|Focus size (hor. x vert.)||350 µm x 350 µm|
|Phone||+49 30 8062 14695|
|More details||KMC-3 XPP|
|Temperature range||10 -- 400 K|
|Pressure range||not applicable|
|Detector||(gated) Pilatus 100k area detector, home-built scintillator with decay time <1 ns, CyberStar detector|
|Sample holder compatibility||maximum sample size:
• 12 x 12 mm2 for standard low-temperature sample holder,
• 20 x 20mm2 for electrical measurement setup,
• up to 40 x 40mm2 can be mounted with special sample holders for room temperature measurements.
|Additional equipment||Laser for optical excitation:
• wavelength 1028 nm
• pulse energy 20 – 400 µJ/cm2
• repetition rate 1 – 1000 kHz
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.