chemRIXS Capabilities

chemRIXS Capabilities for Run 24

The ChemRIXS instrument within the NEH 2.2 hutch is designed to support cutting edge experiments in the fields of chemistry using soft X-rays of the LCLS-II superconducting linac. NEH 2.2  is coupled to the LCLS soft X-ray undulators, which offer a variable gap, providing horizontally polarized X-rays in the photon energy range from 250 eV to 1600 eV. 

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 24, the chemRIXS is planning to commission 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 24

Run 24 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.

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.

The following detectors will be provided to the users:

• 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.
• Andor Newton_SO, 512 X 2048 pixels, 13.5 microns pixel size, capable of full frame read-out at up to 100Hz (i.e. integrating over many X-ray shots).  This CCD detector will be placed outside chemRIXS in the path of the direct beam and will allow for measuring XAS in transmission when using thin sheet jets.
• Portable Varied-Line Spacing (VLS) X-ray Emission Spectrometer (XES).  This is an existing XES spectrometer with resolving power of ~2000, that will be equipped with the above mentioned Andor Newton_SO CCD.  The spectrometer will be mounted in the horizontal plane at 45 degrees with respect to the X-ray beam. The spectrometer can be used simultanaeously with the TFY APDs and the direct beam Andor CCD.

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 spectrometer