ABSTRACT
An X-ray emission spectrometer that can detect the sulfur Kα emission lines with large throughput and a high energy resolution is presented. The instrument is based on a large d-spacing perfect Bragg analyzer that diffracts the sulfur Kα emission at close to backscattering angles. This facilitates the application of efficient concepts routinely employed in hard X-ray spectrometers towards the tender X-ray regime. The instrument described in this work is based on an energy-dispersive von Hamos geometry that is well suited for photon-in photon-out spectroscopy at X-ray free-electron laser and synchrotron sources. Comparison of its performance with previously used instrumentation is presented through measurements using sulfur-containing species performed at the LCLS. It is shown that the overall signal intensity is increased by a factor of â¼15. Implementation of this approach in the design of a tender X-ray spectroscopy endstation for LCLS-II is also discussed.
ABSTRACT
X-ray free-electron lasers (XFELs) provide very intense X-ray pulses suitable for macromolecular crystallography. Each X-ray pulse typically lasts for tens of femtoseconds and the interval between pulses is many orders of magnitude longer. Here we describe two novel acoustic injection systems that use focused sound waves to eject picoliter to nanoliter crystal-containing droplets out of microplates and into the X-ray pulse from which diffraction data are collected. The on-demand droplet delivery is synchronized to the XFEL pulse scheme, resulting in X-ray pulses intersecting up to 88% of the droplets. We tested several types of samples in a range of crystallization conditions, wherein the overall crystal hit ratio (e.g., fraction of images with observable diffraction patterns) is a function of the microcrystal slurry concentration. We report crystal structures from lysozyme, thermolysin, and stachydrine demethylase (Stc2). Additional samples were screened to demonstrate that these methods can be applied to rare samples.
Subject(s)
Crystallography, X-Ray/instrumentation , Enzymes/chemistry , Acoustics , Crystallography, X-Ray/methods , Models, Molecular , Muramidase/chemistry , Protein Conformation , Thermolysin/chemistryABSTRACT
The X-ray Pump-Probe instrument achieves femtosecond time-resolution with hard X-ray methods using a free-electron laser source. It covers a photon energy range of 4-24â keV. A femtosecond optical laser system is available across a broad spectrum of wavelengths for generating transient states of matter. The instrument is designed to emphasize versatility and the scientific goals encompass ultrafast physical, chemical and biological processes involved in the transformation of matter and transfer of energy at the atomic scale.
Subject(s)
Crystallography, X-Ray/instrumentation , Lasers , Particle Accelerators/instrumentation , Spectrometry, X-Ray Emission/instrumentation , X-Rays , California , Energy Transfer , Equipment Design , Equipment Failure Analysis , Lighting/instrumentationABSTRACT
The X-ray Correlation Spectroscopy instrument is dedicated to the study of dynamics in condensed matter systems using the unique coherence properties of free-electron lasers. It covers a photon energy range of 4-25â keV. The intrinsic temporal characteristics of the Linac Coherent Light Source, in particular the 120â Hz repetition rate, allow for the investigation of slow dynamics (milliseconds) by means of X-ray photon correlation spectroscopy. Double-pulse schemes could probe dynamics on the picosecond timescale. A description of the instrument capabilities and recent achievements is presented.