Hybrid diamond-silicon angular-dispersive x-ray monochromator with 025-meV energy bandwidth and high spectral efficiency

Abstract

We report on the design, implementation, and performance of an x-ray monochromator with ultra-high energy resolution (ΔE/E ≃ 2.7 × 10(-8)) and high spectral efficiency using x rays with photon energies E ≃ 9.13 keV. The operating principle of the monochromator is based on the phenomenon of angular dispersion in Bragg back-diffraction. The optical scheme of the monochromator is a modification of a scheme reported earlier [Shvyd'ko et al., Phys. Rev. A 84, 053823 (2011)], where a collimator/wavelength selector Si crystal was replaced with a 100-μm-thick type IIa diamond crystal. This modification provides a very-small-energy bandwidth ΔE ≃ 0.25 meV, a 3-fold increase in the aperture of the accepted beam, a reduction in the cumulative angular dispersion rate of x rays emanating from the monochromator for better focusing on a sample, a sufficient angular acceptance matching the angular divergence of an undulator source (≈ 10 μrad), and an improved throughput due to low x-ray absorption in the thin diamond crystal. The measured spectral efficiency of the monochromator was ≈ 65% with an aperture of 0.3 × 1 mm(2). The performance parameters of the monochromator are suitable for inelastic x-ray spectroscopy with an absolute energy resolution ΔE < 1 meV.

X-ray Echo Spectroscopy

“…Therefore, optical designs of the dispersing elements have to be found featuring both large D ∪ and ∆E ∪ . Figures 3 and 4 show representative examples of multi-crystal CDDWtype inline dispersing elements [14][15][16] of the defocusing and refocusing systems, respectively, with the required cumulative dispersion rates, asymmetry factors, and with bandwidths ∆E ∪ 5.5−9 meV, i.e., ∆E ∪ /∆ε 55−90, designed for use with 9.1-keV photons. These examples are modifications of the dispersing elements designs presented in [9].…”

“…In-line four-crystal CDDW-type dispersing optics [14][15][16] D 2 ), and wavelength-selecting (W) crystals, which can be arranged in different scattering configurations. In a general case, the scattering configuration is defined as (φ 1 s 1 , φ 2 s 2 , φ 3 s 3 , φ 4 s 4 ).…”

An X-ray diffractometer using mirage diffraction

“…X-rays with an energy resolution of 0.45 meV were obtained by using Si(13 13 13) reflection with B = 89.98 for X-rays of 25.70 keV (Verbeni et al, 1996). Another monochromator with an energy resolution of sub-meV was designed by combining asymmetric reflection with back reflection (Baron et al, 2001;Stoupin et al, 2013). Stoupin et al designed a monochromator with high spectral efficiency by combining asymmetric reflection from an asymmetrically cut diamond with back reflection from a silicon crystal.…”

Ultra-high-resolution inelastic X-ray scattering at high-repetition-rate self-seeded X-ray free-electron lasers

“…Additionally, the spectral contrast improved by an order of magnitude compared with traditional IXS spectrometers (Burkel et al, 1987;Sette et al, 1995;Masciovecchio et al, 1996;Baron et al, 2001;Sinn et al, 2001;Said et al, 2011). To sharpen the desired resolution to 0.1 meV and 0.02 nm À1 and to ensure higher count rates, we propose to further develop the angular-dispersive X-ray optical scheme Stoupin et al, 2013) replacing scanning IXS spectrometers with broadband imaging spectrographs .…”