chemRIXS Standard Configuration

chemRIXS Liquid Standard Configuration for Run 25

The chemRIXS endstation will provide a liquid standard configuration for time-resolved pump-probe XAS and/or RIXS/XES experiments on liquids/solution utilizing in-vacuum liquid jet delivery with sample recirculation capability. Tables below summarize the X-ray and laser capabilities for the SC accelerator and OPCPA laser system. For Run 25, the chemRIXS will provide a new high throughput RIXS spectrometer and upgraded downstream detection scheme for transmission experiments. Please contact the instrument scientist Kristjan Kunnus for any questions regarding the liquid standard configuration or any other questions (e.g. non-standard experiments with solid samples and/or advanced X-ray modes). 

Guidelines and Performance Parameters for Run 25

Run 25 will make use of the new superconducting LCLS-II accelerator which will operate at repetition rates up to 33 kHz. The OPCPA laser system with 800 nm fundamental will be synchronized to the X-rays and available for pump-probe experiments.

The following detectors will be provided to the users:

• Variable-Line Spacing (VLS) Spectrometer.  This is an existing 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 100 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.

The community is encouraged to propose experiments focusing on the following techniques:

• Time-resolved RIXS/XES
• 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 VLS or SVLS spectrometer

Performance Parameters 

The new OPCPA laser system will offer short (< 25 fs) 800 nm laser pulses. Harmonics of these pulses can be generated (400/266 nm) and  Vis-OPA providing 480 - 900 nm is available.