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arXiv · 1407.7489

Bent crystal spectrometer for both frequency and wavenumber resolved x-ray scattering at a seeded free-electron laser

Ulf Zastrau·Luke B. Fletcher·Eckhart Foerster·Eric Ch. Galtier·Eliseo Gamboa·Siegfried H. Glenzer·Philipp Heimann·Heike Marschner·Bob Nagler·Andreas Schropp·Ortrud Wehrhan·Hae Ja Lee
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Abstract

We present a cylindrically curved GaAs x-ray spectrometer with energy resolution $ΔE/E = 1.1\cdot 10^{-4}$ and wave-number resolution of $Δk/k = 3\cdot 10^{-3}$, allowing plasmon scattering at the resolution limits of the Linac Coherent Light Source (LCLS) x-ray free-electron laser. It spans scattering wavenumbers of 3.6 to $5.2/$Å in 100 separate bins, with only 0.34\% wavenumber blurring. The dispersion of 0.418~eV/$13.5\,μ$m agrees with predictions within 1.3\%. The reflection homogeneity over the entire wavenumber range was measured and used to normalize the amplitude of scattering spectra. The proposed spectrometer is superior to a mosaic HAPG spectrometer when the energy resolution needs to be comparable to the LCLS seeded bandwidth of 1~eV and a significant range of wavenumbers must be covered in one exposure.

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Ulf Zastrau, Luke B. Fletcher, Eckhart Foerster, Eric Ch. Galtier, Eliseo Gamboa, Siegfried H. Glenzer, Philipp Heimann, Heike Marschner, Bob Nagler, Andreas Schropp, Ortrud Wehrhan, Hae Ja Lee. 2014-07-28. Bent crystal spectrometer for both frequency and wavenumber resolved x-ray scattering at a seeded free-electron laser. https://doi.org/10.1063/1.4894821

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