XCS Standard Configurations

Configuration #1
Configuration #2

XCS Standard Configuration #1 for Run 25

#1 Time-resolved solution scattering (XSS) & emission/absorption spectroscopy (XES/XANES)

Types of Experiments

With this standard configuration, XCS will be able to support time-resolved wide-angle scattering (XSS) and X-ray emission (XES) or near-edge absorption spectroscopy measurements (XANES) for the study of photo-excited molecular dynamics in the solution phase.

A 2D epix100 detector or a von Hamos spectrometer will be mounted on top of the sample chamber (due to the vertical polarization of the undulators) to measure the XANES or the XES signals respectively. The von Hamos spectrometer can cover the following X-ray emission lines: Mn Kß1,3, Kß2,5 and Kα, Fe Kß1,3 and Kß2,5, Co Kß1,3 and Kß2,5, Ni Kß1,3 and Kß2,5, Ti Kß1,3 and Kß2,5 and V Kα, please contact the XCS staff for other elements.

X-ray and X-ray Focus

The XCS Instrument can operate in pink mode (6.5 to 25 keV) or in scannable monochromatic mode using the channel cut monochromator (CCM) with Si(111) crystals (6.5 to 25keV). We expect an average photon flux of ~10¹² photons/pulse in pink and 10¹⁰ photons/pulse in monochromatic mode.

Refractive Be lenses will be available to deliver a beam size ranging from 5 to 100 μm at the sample location. For experiments that don’t require specific photon energy and for scheduling purposes the default photon energy of 9.831keV will be used for standard configuration.

Optical Pump Lasers

Time-resolved experiments employing tunable femtosecond pulses will be supported under this standard configuration. In addition to the 800/400/266 nm 50 fs Ti:Sapphire fundamental/2nd/3rd harmonic wavelengths, an OPA will be available to cover wavelengths in the visible to near-IR range: 480 - 2400 nm. The optical pump beam will be propagating collinearly with the X-ray beam with about 2 degree crossing angle. We note that the efficiency of the optics and the performance of the laser and the OPA will not be the same for the entire wavelength range. The achievable peak intensity/fluence will be determined by the existing optical system and will not be modified. Contact the XCS scientists to discuss specific needs and to confirm whether they can be achieved in this standard configuration of the laser.

Timing diagnostics

The spectral-encoding based timing tool will be available to provide shot-to-shot jitter measurement. We expect a time resolution of 100 fs considering the pump/probe pulse duration as well as the jitter correction accuracy.

Sample Manipulation and Temperature Control

A helium purged sample chamber including sample monitoring and cleanup slits will be used to house the liquid jet, with Kapton windows to allow X-ray scattering and emission to be measured by detectors outside the chamber. A horizontal liquid jet driven by HPLC pumps will be used to deliver the sample into the interaction point.

Round Jet diameters of the following size are available: 20, 30, 40, 50, 75, 100, 125, 150, 175, 200, 250, 300, 500.

Flat-sheet thicknesses of the following size are available: 19, 25, 38, 50, 75, 100, 125, 175, 188, 250.

Every user group accepted and scheduled to use the XCS standard configuration will be strongly advised to test the injection of their sample at the LCLS Sample Characterization Lab prior to the experiment.

Detectors

An epix10k-2.1M detector will be mounted downstream of the chamber for the measurement of the forward scattering. The X-ray emission spectra will be measured by an epix100 detector.

XCS Instrument Staff

Matthieu Chollet, Patrick Kramer, Gourab Chatterjee, Roberto Alonso-Mori, Sanghoon Song, Tim B. van Driel.

Parameter Table

To be considered for scheduling in this standard configuration, users will be required to include a table in the proposal that lists the specific experimental parameters to ensure compatibility with these configurations. If the experimental parameters are not compatible with the standard configuration or if the table of parameters is incomplete, the proposal will be reviewed and considered for scheduling as general user proposal. Please see the table of required parameters. No fundamental changes to the standard configurations will occur, but some details of the configuration may be updated in response to inquiries, so users should recheck the website before submitting your proposal to confirm that you have the latest information. Address any questions to the instrument staff.

XCS Standard Configuration #2 for Run 25

#2 Time-resolved hard X-ray coherent scattering and small angle scattering measurements

Types of Experiments

With this standard configuration, XCS will be able to support time-resolved hard X-ray coherent scattering and small angle scattering on various condensed matter systems. Scattering geometry is limited to the horizontal plane.

X-ray and X-ray Focus

X-rays will be delivered through the large offset monochromator using the diamond (111) configuration up to 12keV. We expect an average photon flux of 1010/pulse after the monochromator. Refractive Be lenses will be available to deliver a beam size ranging from 3 to 200 μm at the sample. For experiments that don’t require specific photon energy and for scheduling purposes the default photon energy of 9.831keV will be used for standard configuration.

Optical Pump Lasers

Time-resolved experiments employing tunable femtosecond pulses will be supported under this standard configuration. In addition to the 800/400 nm 50 fs Ti:Sapphire fundamental/2nd harmonic wavelengths, an OPA will be available to cover the wavelength range of 480-2400 nm. The optical pump beam will be propagating collinearly with the X-ray beam with about 2 degree crossing angle. We note that the efficiency of the optics and the performance of the laser and the OPA will not be the same for the entire wavelength range. The achievable peak intensity/fluence will be determined by the existing optical system and will not be modified. Contact the XCS scientists to discuss specific needs and to confirm whether they can be achieved in this standard configuration of the laser.

Timing diagnostics

Sample Manipulation and Temperature Control

The XCS diffractometer will be used to position and orient the sample with 3 degrees of freedom in order to diffract in the horizontal plane. The sample mount shall fit the standard Huber goniometer head. The Oxford cryostream system will be available to provide in-air sample cooling down to 100 K. Heating up to 350 K can be delivered by the same system as well.

Every user group accepted and scheduled to use the XCS standard configuration will be required to know the crystallographic orientation of their sample.

Detectors

An epix10k-2.1m or epix100 detectors will be mounted on the Large Angle Detector Mover (LADM). The LADM provides two sample detector distances : 4 and 8 m. It can rotate up to 55° scattering angle in the horizontal plane. It provides an evacuated fly path between the diffractometer and the detector. It also provides three different vacuum beamstops upstream the exit window. The LADM provides Small Angle X-ray Scattering capabilities for 2θ=0°. At the end of the LADM, a vertical and horizontal translation stages allow to move a 2-dimensional detector to be located at a position of interest.