chemRIXS Standard Configurations

chemRIXS Liquid Standard Configuration

The chemRIXS endstation provides a liquid standard configuration for time-resolved pump-probe XAS and/or RIXS/XES experiments on liquids/solution. This configuration operates with monochromatized X-ray beam with DE/E ~ 2000. In-vacuum liquid jets are used for sample delivery. Sample recirculation capability is part of the standard setup. The endstation provides a high throughput RIXS spectrometer (RP~2000). In-vacuum APDs are available for fluorescence detection and downstream beam intensity detector(s) can be utilized for transmission experiments. Typical pump-probe time-resolution is on the order of 100 fs. Tables below summarize the X-ray and laser capabilities for Run 27 (120 Hz CuRF beam). High-repetition rate SCRF beam is currently not available due to the LCLS-II HE upgrade. 

chemRIXS FZP Standard Configuration

For Run 27 (120 Hz), the chemRIXS endstation will provide a standard configuration that allows dispersive detection of X-rays with an in-line transmission Fresnel Zone Plate (FZP) spectrometer. Typical experiment envisioned for this configuration will utilize unmonochromatized X-rays (SASE or attosecond XLEAP beam) which are transmitted trough a sheet jet in chemRIXS. The X-ray spectrum is subsequently detected shot-by-shot using the downstream FZP spectrometer.

Please contact the instrument scientist Kristjan Kunnus for any questions regarding the standard configurations or any other questions (e.g. non-standard experiments with solid samples and/or advanced X-ray modes). 

Guidelines and Performance Parameters for Run 27

Run 27 will make use of the LCLS-I accelerator which will operate at the 120 Hz repetition rate. The CARBIDE laser system with 1030 nm fundamental will be synchronized to the X-rays and available for pump-probe experiments.
The community is encouraged to propose experiments focusing on the following techniques:

• Time-resolved XAS, which can be implemented in three modes:
  • Direct transmission (for samples delivered in the form of a thin sheet jet)
  • TFY mode, using the in-vacuum APD
  • Partial Fluorescence Yield (PFY) mode, using the SVLS spectrometer
• Unmonochromatized experiments
  • Utilizing advanced XLEAP modes (attasecond single or double pulses).
  • Dispersive detection with in-line FZP spectrometer downstream of chemRIXS IP.

Due to incident flux limitations, time-resolved RIXS experiments are discouraged.

Performance Parameters 

The new CARBIDE laser system will offer 1030 nm laser pulses compressed to <30 fs. The fundamental, 2nd, 3rd and 4th harmonic will be available for experiments. Tunable Vis-OPA will not be available in Run 27.

chemRIXS detection techniques

• Variable-Line Spacing (VLS) Spectrometer.  This is a spectrometer with resolving power of ~1300 that is equipped with the Andor Newton_SO CCD (512 X 2048 pixels, 13.5 microns pixel size).  The CCD will integrate over many X-ray shots, with read-out rates up to 120 Hz in full-vertical-binning mode or up to 1 Hz in image mode. The spectrometer will be mounted in the horizontal plane at 45 degrees with respect to the X-ray beam.
• High-throughput Spherical Variable-Line Spacing (SVLS) Spectrometer.  This is a new spectrometer with nominal resolving power of 2000 that is equipped with the AXIS-SXR-60 CMOS detector (6144 X 6144 pixels, 10 microns pixel size).  The CMOS will integrate over many X-ray shots, with read-out rates up to 100 Hz in cropped image mode. The spectrometer will be mounted in the horizontal plane at 90 degrees with respect to the X-ray beam. The spectrometer is currently under installation/commissioning.
• Avalanche PhotoDiodes (APD).  The APDs are single-photon sensitive fast detectors suitable for X-ray Absorption Spectroscopy (XAS) in Total Fluorescence Yield (TFY) mode.  These detectors will be mounted on an in-vacuum rotatable stage and can be placed in the horizontal scattering plane. APDs are single shot detectors and can be read-out at 33 kHz.
• Transmission-XAS detectors for measuring transmitted beam intensity downstream of ChemRIXS when using thin sheet jets.
  • Andor Newton_SO, 512 X 2048 pixels, 13.5 microns pixel size, capable of read-out up to 100 Hz in full-vertical-binning mode and 1 Hz in full image mode. Will be used in integrating mode with high rep.-rate beam, i.e. accumulating signal over many X-ray shots. This is an existing CCD camera used before with 120 Hz beam.
  • ePixM, 384 X 764 pixels, 50 microns pixel size, capable of full image read-out up to 5 kHz. This detector is currently in the testing phase.
  • Single-shot APD for indirect detection of transmitted beam by a fluorescence from a target.

The RIXS/XES spectrometers can be used simultaneously with the TFY APDs and the transmission detectors.