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An Office of Science User Facility

Macromolecular Femtosecond Crystallography (MFX)


Scientific Capabilities

Scientific Applications

Femtosecond Crystallography

Time-resolved scattering with hard x-rays

Techniques and Scattering Geometry

Macromolecular Crystallography

Forward scattering on fixed-mounted samples,
and in liquid jets

Small Angle X-ray Scattering

Wide Angle X-ray Scattering

X-ray Emission Spectroscopy


Source Parameters

Photon Energy

5-11 keV for the 1st harmonic*

Up to 25  keV for 2nd and 3rd harmonic

Source Size

60 x 60 µm2 (HxV) FWHM @ 8.3 keV

78 x 78 µm2 (HxV) FWHM @ 2 keV

Source Divergence

2 x 2 µrad2 (HxV) FWHM @ 8.3 keV

~7 x 7 µrad2 (HxV) FWHM @ 2 keV

Repetition Rate

120 , 60, 30, 10 Hz, Single shot mode

Pulse Duration

30-100 fs (high charge mode)

<10 fs (low charge mode)

Pulse Energy

1-4 mJ  (high charge mode)

~ 0.2 mJ  (low charge mode)

Photons per Pulse

~1 x 1012 (high charge mode @ 8.3 keV)

~1 x 1011 (low charge mode @ 8.3 keV)

* Energies below 5 keV are in principle usable but the beam size at the end station is large leading to poor focusing performance and reduced flux. Also, transmission of the beam into atmospheric pressure leads to significant losses. LCLS-II will extend the energy range up to 20 keV.

Photon Beam Properties

Focusing Capability

Beryllium Lenses in Hutch 4.5 (~1 µm focus)

Beam Size at Sample (8 keV)

(Calculated for perfect optics)

0.7 x 0.7 µm2 FWHM

Beam Divergence

(Calculated for perfect optics)

~0.3 x 0.3 mrad2 FWHM

Energy Range

5-11 keV (1st harmonic using LCLS-I)

5-20 keV (1st harmonic using LCLS-II)

11-25  keV (2nd and 3rd harmonic using LCLS-I)

20-25  keV (2nd and 3rd harmonic using LCLS-II)

Energy Resolution ΔE/E

~0.2% (bandwidth of the LCLS beam)
No monochromator currently

Sample Environment and Detector

Sample Environment

Atmospheric pressure

Fixed sample on grids at room temperature

Fixed sample on grids at cryogenic temperature

Helium atmosphere

Humidity control

Sample Injectors

Liquid Jets of various kinds




SLAC SLAC National Accelerator Laboratory, Menlo Park, CA
Operated by Stanford University for the U.S. Dept. of Energy