This instrument will be the primary station for the majority of the experiments performed at ESA (see Fig's. 1 & 2). The focus of this instrument is to ensure the ability to use the ‘tender’ X-ray energy spectrum (2-5 keV), which requires either vacuum or He atmosphere and a minimum of windows.
The preliminary description of this instrument includes:
- a 6D sample manipulator located at the X-ray focus position capable of moving small samples around in X,Y,Z motions, with optional control of pitch, roll, and rotation
- a von Hamos spectrometer consisting of 2 x 2 crystals and 2 pixel detectors, enclosed in a vacuum chamber, capable of measuring from 1 to 12.4 keV emitted X-ray photons with a source point at the X-ray focus
- a large 2D detector (16M Jungfrau) with a central hole and mounted on a vacuum flange for scattering measurements along the direct beam
- a sample environment capable of neutral atmosphere or vacuum within which is located the sample manipulator and coupled to the last element of the beamline and the von Hamos spectrometer, to allow for complete vacuum environment if necessary
- the entire unit is mounted on a motorized table, allowing for it to be moved to align the ESA Prime setup to the X-ray spot for both focused and unfocussed X-rays
- the ESA Prime unit will have three horizontal positions, allowing for two different scattering geometries on the 2D detectors and a position fully out of the beam path
Because of the two crystal pairs in the XES spectrometer ESA Prime can measure two signals simultaneously. Examples of this would be the Kα; and Kβ; emission lines from a 3d transition metal, or some combination of Inelastic X-ray signals in combination with an off-resonant signal.
ESA Prime is focused on the tender X-ray regime from 2-5 keV. To cover this energy range several different crystals are required. Examples of these crystals are shown below with the corresponding photon energies and Bragg angles (Fig. 3). The Bragg angle range covered by the ESA Prime spectrometer is from 40-80°.
ESA Prime is also designed for scattering experiments, including Wide-Angle X-ray Scattering (WAXS) and Serial Femtosecond Crystallography (SFX). Both types of experiments use a large 2D detector (Fig. 4) in-line with the beam. ESA Prime is designed to achieve at 10 cm sample-to-detector distance. The maximum Qmax of the detector at 12.4 keV is 7 Å-1, which corresponds to around 1 Å resolution for crystallography experiments.
J. Szlachetko, C. J. Milne, J. Hoszowska, et al., Struct. Dyn. 1, 021101 (2014).