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The chemRIXS Instrument for the LCLS-II X-Ray Free Electron Laser

David J. Hoffman, Douglas Garratt, Matthew Bain, Christina Y. Hampton, Benjamin I. Poulter, Jyoti Joshi, Giacomo Coslovich, Frank P. O'Dowd, Daniel P. DePonte, Alexander H. Reid, Lingjia Shen, Daniel Jost, Mina R. Bionta, Joshua J. Turner, Ming-Fu Lin, Philip Heimann, Stefan P. Moeller, Jake D. Koralek, Tyler Johnson, K Ninh, Raybel Almeida, Adam Berges, Stephanie Fung, Shuai Li, Eetu Pelimanni, Amke Nimmrich, Munira Khalil, Linda Young, Thomas J. A. Wolf, Kristjan Kunnus, Georgi L. Dakovski

Abstract

The chemRIXS instrument at the Linac Coherent Light Source offers new opportunities for studying solution-phase systems with time-resolved soft X-ray spectroscopy through the recently commissioned high-repetition-rate LCLS-II X-ray free electron laser. The orders-of-magnitude X-ray flux improvement provided by the superconducting accelerator, combined with corresponding advances in the optical laser system and the liquid jet recirculation system, enables studies on dilute systems with high signal-to-noise compared to what was possible with the LCLS-I copper accelerator. These capabilities open up time-resolved X-ray absorption spectroscopy and resonant inelastic X-ray scattering to entirely new classes of samples, as well as enabling the development of new soft X-ray spectroscopies on liquid samples. An overview of the beamline components and the first LCLS-II commissioning results are presented.

The chemRIXS Instrument for the LCLS-II X-Ray Free Electron Laser

Abstract

The chemRIXS instrument at the Linac Coherent Light Source offers new opportunities for studying solution-phase systems with time-resolved soft X-ray spectroscopy through the recently commissioned high-repetition-rate LCLS-II X-ray free electron laser. The orders-of-magnitude X-ray flux improvement provided by the superconducting accelerator, combined with corresponding advances in the optical laser system and the liquid jet recirculation system, enables studies on dilute systems with high signal-to-noise compared to what was possible with the LCLS-I copper accelerator. These capabilities open up time-resolved X-ray absorption spectroscopy and resonant inelastic X-ray scattering to entirely new classes of samples, as well as enabling the development of new soft X-ray spectroscopies on liquid samples. An overview of the beamline components and the first LCLS-II commissioning results are presented.

Paper Structure

This paper contains 28 sections, 10 figures, 5 tables.

Table of Contents

  1. Introduction
  2. Instrument Components
  3. XFEL Source
  4. Beamline Components
  5. The chemRIXS Chamber
  6. Detectors
  7. Emission Spectrometer
  8. Avalanche Photodiodes
  9. Transmission XAS Detector
  10. Transmission Spectrometer
  11. Bursting Operation
  12. Optical Lasers
  13. Laser System
  14. Laser/ X-ray Timing
  15. Arrival Time Monitor (ATM)
  16. ...and 13 more sections

Figures (10)

  • Figure 1: Schematic overview of the principal X-ray beamline components and optical laser components for the chemRIXS instrument. Purple indicates the X-ray beam, red indicates the OPCPA fundamental (800 nm), and blue indicates the variable-wavelength optical laser beam delivered to the chemRIXS IP. KB: Kirkpatrick-Baez Mirror, ATM: Arrival Time Monitor, OPCPA: Optical Parametric Chirped Pulse Amplifier, OPA: Optical Parametric Amplifier, FIM: Fluorescence Intensity Monitor, APDs: Avalanche Photodiodes, Pol.: Polarizer, $\lambda/2$: half-waveplate.
  • Figure 2: Monochromator resolving power ($\Delta E/E$), beamline transmission, and pulse stretching for the low resolution grating used at chemRIXS for 300 to 1000 eV for select constant focal factors (Cff) achievable by the monochromator. All values FWHM. Resolving power and transmission correspond to approx. 30 $\mu$m exit slit width - equal to the width of monochromatic image at the exit slit plane. Transmission calculated for B$_4$C coating. More details can be found in a prior publication.nicolas2022p
  • Figure 3: A. Top down view of the main chemRIXS chamber and injector load-lock chamber. The X-ray path is indicated with a red arrow. The principle components are indicated. B. Isometric view of the chemRIXS IP. The injector is shown inserted in its experimental configuration.
  • Figure 4: Model of the VLS spectrometer.
  • Figure 5: Model of the APD stage.
  • ...and 5 more figures