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.
Methods
Remote access
depends on experiment - please discuss with Instrument Scientist
| Beamline data | |
|---|---|
| Energy range | 2 - 14 keV |
| Energy resolution | 1/5000 - 1/4000 |
| Flux | 1e11 photons/s |
| Polarisation | horizontal |
| Focus size (hor. x vert.) | 350 µm x 350 µm |
| Phone | +49 30 8062 14695 |
| More details | KMC-3 XPP |
| Station data | |
| 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 |
| Manipulators | not applicable |
| 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.