SwissFEL Alvra experimental station
Alvra is currently in a combined Pilot Experiment/Commissioning phase of operation. A summary of the experimental station parameters follows.
| Photon energy range | 2 – 12 keV |
|---|---|
| Beam profile | Measured focus 20 x 30 µm2 (FWHM) at 2 and 4.5 keV |
| Measured focus 2 x 2 µm2 (FWHM) at 12 keV | |
| Unfocused beam: ~1 x 1 mm2 (FWHM) energy dependent | |
| Bandwidth | SASE 0.5% (pink beam) |
| Monochromatic: Si(111), Si(311) and InSb(111) | |
| Sample Environment | From vacuum (5 x 10-4 mbar) up to atmospheric pressure (He or N2) |
| Sample delivery systems | Liquid jet for chemistry: |
| - Flat jet (100, 200 and 300 µm) with gear or peristaltic pump | |
| - Round jet (20-100 µm) with HPLC pump | |
| LCP viscous injector (50-100 µm) | |
| GDVN injectors tested in chamber | |
| Solid samples | |
| Detectors and Spectrometers | 16M Jungfrau forward scattering detector at 10 cm distance |
| 2 x 2 crystal von Hamos dispersive X-ray emission spectrometer (1-12.4 keV) | |
| Diodes for x-ray absorption measurements |
| Photon energy range | 6 – 12 keV |
|---|---|
| Beam profile | Design focus 100 x 100 µm2 (FWHM) |
| Unfocused beam: ~1 x 1 mm2 (FWHM) energy dependent | |
| Bandwidth | SASE 0.5% (pink beam) |
| Monochromatic: Si(111), Si(311) and InSb(111) | |
| Sample Environment | Atmospheric conditions |
| Sample delivery systems | Liquid jet for chemistry: |
| - Flat jet (100, 200 and 300 µm) with gear or peristaltic pump | |
| - Round jet (20-100 µm) with HPLC pump | |
| LCP viscous injector (50-100 µm) | |
| Solid samples | |
| Detectors and Spectrometers | 3 crystal von Hamos dispersive X-ray emission spectrometer with 1M Jungfrau detector |
| Diodes for x-ray absorption measurements |
| Primary pump source | 800 nm, 35 fs FWHM, 10 mJ (Ti:Sapphire) |
|---|---|
| Secondary pump sources | 240 nm – 2.5 micron (OPA with additional nonlinear conversion options). At present pulse energies at the sample location for 240-400 nm have been measured in the range of 10-30 µJ. We expect pulse energies of 150-500 µJ between 400 nm and 780 nm; 150-500 µJ between 1 µm and 2.5 µm. Pulse durations are expected to be approximately 50 fs fwhm. |
Current Highlights and News
First serial femtosecond crystallography experiment using SwissFEL’s large bandwidth X-ray pulses
The typical mode of operation at XFEL facilities uses the so-called self-amplified spontaneous emission (SASE) process to generate the short, bright X-ray pulses. This mode of operation is stochastic in nature, causing some variance in intensity and spectrum on a shot-to-shot basis, which makes certain types of crystallographic measurements much more challenging.
Towards X-ray Transient Grating Spectroscopy at SwissFEL
The high brilliance of new X-ray sources such as X-ray Free Electron Laser opens the way to non-linear spectroscopies. These techniques can probe ultrafast matter dynamics that would otherwise be inaccessible. One of these techniques, Transient Grating, involves the creation of a transient excitation grating by crossing X-ray beams on the sample. Scientists at PSI have realized a demonstration of such crossing by using an innovative approach well suited for the hard X-ray regime.
First femtosecond protein pump-probe measurements at SwissFEL
A major milestone in the commissioning of SwissFEL has been reached: the first pump-probe experiments on proteins have been successfully carried out. Crystals of several retinal-binding proteins were delivered in a viscous jet system and a femtosecond laser was used to start the isomerization reaction. Microsecond to sub-picosecond snapshots were then collected, catching the retinal proteins shortly after isomerization of the chromophore.