ID23-2 Summary

The ID23 beamlines are part of the Macromolecular Crystallography Group which supports the study and structure determination of biological macromolecules and are composed of two independent end-stations. ID23-1 is a fully tunable beamline from 6 to 20 keV energy (2.07 Å to 0.62 Å). ID23-2 operates at a fixed energy and is in particular specialized to perform experiments with very small protein crystals and for serial crystallography. The X-ray sources for the two stations are canted undulators (separated by 1.5mrad) that are mounted on a special carriage on the storage ring. The ID23-1 undulator is a U35 (allowing tuning of the energy across harmonics) and for ID23-2 a U20.2 is used which is a pseudo-monochromatic source with a single first harmonic at 14.2keV/0.873 Å.

ID23-2 delivers a flux of about 2.4x1012 ph/s in a microfocus beam of ~10x4 µm. Since the recent upgrade the beam is vertically focussed by CRLs and horizontally focussed by a mirror in half-Kirkpatrick-Baez (KB) geometry. The beamline is equipped with a MD3-UP microdiffractometer with a vertical spindle that can perform very fast mesh scans and is compatible with in-situ data collection for low-profile crystallization plates. A FlexHCD sample changer robot has been installed that can take up to 23 Unipucks (SPINE Pucks/SC3 Baskets as well as non-SPINE sample holders are not supported anymore, please see sample changer section for details). The detector is a PILATUS3 X 2M with a maximum frame rate of 250 Hz for the full surface and 500 Hz when using exclusively the central modules of the detector.

Scientific Applications

Protein crystal samples are becoming ever smaller, with today's samples typically around 10 to 100 microns in size. With the development of third generation synchrotron radiation sources, it is now possible to have access to a focused and very intense hard X-ray beam in the µm-range. ID23-2 produces a focused beam of less than 10 µm in diameter (FWHM) to allow to nable the study of microcrystals as well as facilitate serial crystallographic experiments.

relevant publications:

Small is beautiful: protein micro-crystallography ; Cusack S, Belrhali H, Bram A, et al.  Nature Structural Biology 5: 634-637 Suppl. S AUG 1998

Protein microcrystals and the design of a microdiffractometer: current experience and plans at EMBL and ESRF/ID13 ; Perrakis A, Cipriani F, Castagna JC, et al.  Acta Crystallographica Section D-Biological Crystallography 55: 1765-1770 Part 10 OCT 1999

The ID23-2 structural biology microfocus beamline at the ESRF, David Flot et al., Journal of Synchrotron Radiation. 2010 January 1; 17(Pt 1): 107–118.

Techniques Available

  • Microfocus beam
  • Fixed wavelength rapid data collection (SAD/MIR)
  • Fast mesh scans
  • In-situ data collection available upon request
  • HC1 humidity control device available upon request


When coming on ID23-2 as a user, you will have to deal with a small and intense beam. Keeping a 2000 µm3 (about 20 x 10 x 10 µm3) crystal in a 10 µm diameter beam needs good beam stability AND accurate crystal centring.

To maximise success rates and data quality, we recommend using the minimum amount of cryoprotection possible (or no cryoprotectant at all).  This can be important for reducing background as well as optical centering of crystals, although X-ray centering is also available on the beamline.

Beam drifts

In normal operating conditions, small beam drifts (variations in position of less than 10 µm in both vertically and horizontally directions) have been regularly observed over a period of 12 hours. Such variations are expected and are mainly driven by experimental hutch temperature variations. In order to minimize those it is highly advisable to enter the control cabin with as few persons as possible at the same time and to open both the door of the experimental hutch as well as the door outside the experimental hutch only when necessary.

The possibility of beam drift makes regular beam position checks necessary. This can simply be done by using the center beam button in MXCube.


EMBL has provided a scientist position to operate the ID23-2 beamline.