Resonant inelastic x-ray scattering spectrometer with 25 meV resolution at Cu K-edge

An unparalleled resolution is reported with an inelastic x-ray scattering instrument at the Cu K-edge. Based on a segmented concave analyzer, featuring single crystal quartz (SiO_{2}) pixels, the spectrometer delivers a resolution near 25 meV (FWHM) at 8981 eV. Besides the quartz analyzer, the performance of the spectrometer relies on a four-bounce Si(553) high-resolution monochromator and focusing Kirkpatrick-Baez optics. The measured resolution agrees with the ray tracing simulation of an ideal spectrometer. We demonstrated the performance of the spectrometer by reproducing the phonon dispersion curve of a beryllium (Be) single crystal

High resolution monochromators for spectroscopy at high-energy Mössbauer transitions at the Dynamics Beamline P01

Monochromatization of x-rays with high energy resolution is a vital demand for several structure and dynamics investigation techniques in condensed matter. High-efficient monochromatization is a key point for experiments with nuclear resonant scattering of synchrotron radiation since such experiments rely on high narrow band photon flux. Particularly, the monochromatization becomes more challenging for the studies of Mössbauer transitions with the energies 30-80 keV when the spectral reflectivity of silicon crystals becomes low.A free choice of the selected energy together with high energy resolution can be achieved by backscattering from a low symmetry crystal, in particular, from an Al2O3 sapphire crystal [1]. Due to the lower crystal symmetry and higher Debye-Waller factor of Al2O3 as compared to silicon, sapphire crystals provide a wide choice of energies and higher spectral reflectivity at high photon energies. In backscattering geometry the temperature of the crystal defines the interplanar distances in the crystal and the energy of the reflected photons. The dynamical theory of x-ray scattering predicts the energy width of the back-reflections, ~0.1-3 meV, in an ideal sapphire single crystal in the 5-100 keV energy range. Thus, in order to maintain such high resolution the temperature of the crystal should be tuned with a relative precision of 0.1-1 mK in the 120-400 K temperature range, respectively [2,3,4]. Here, we present the backscattering monochromator developed and installed at the Dynamics Beamline P01 at PETRA III. The monochromator consists of a flow cryostat with sub-mK temperature stability hosting a high-quality sapphire crystal. The efficiency of the monochromator has been tested with nuclear resonance scattering on 119Sn at 23.88 keV. An energy resolution of 1.4 meV has been obtained. The monochromator is suitable for nuclear inelastic scattering experiments at transitions energies from 20 to 50 keV , e.g., 151Eu at 21.5 keV, 125Te at 35.5 keV, 121Sb at 37.1 keV 129Xe at 39.6 keV.The nuclear resonances with transitions at 60-80 keV can be studied by other techniques which profits from the lower x-ray absorption of silicon detectors in this energy range [5]. By means of this technique we report on the first observation of nuclear resonance scattering on 193Ir at 73.04 keV and discuss first scientific applications on iridate compounds.[1] Yu. V. Shvyd’ko, X-Ray Optics, Springer Ser. Optical Science, V.98 (2004)[2] M. Lucht, M. Lerche, H.-C. Wille et al., J. Appl. Cryst. V.36 (2003), p. 1075[3] I. Sergueev, H.-C. Wille, R.P. Hermann et al., J. Synch. Rad. V.18 (2011), p.802[4] B. Klobes, A. Desmedt, I. Sergueev et al., Europhys. Lett., V.103 (2013), p.36001[5] D. Bessas, D.G. Merkel, A.I. Chumakov et al. Phys. Rev. Lett. 113 (2014), p.14760

IRIXS Spectrograph: an ultra high-resolution spectrometer for tender RIXS

The IRIXS spectrograph represents a new design of a ultra high-resolution resonant inelastic X-ray scattering (RIXS) spectrometer that operates at the Ru L3-edge(2840 eV). First proposed in the field of hard X-rays by Shvyd'ko (2015), the X-ray spectrograph uses a combination of laterally graded multilayer mirrors and collimating/dispersing Ge(111) crystals optics in a novel spectral imaging approach to overcome the energy resolution limitation of a traditional Rowland-type spectrometer(Gretarsson et al., 2020). In combination with a dispersionless nested four-bounce high resolution monochromator design that utilizes Si(111) and Al$_2$O$_3$(110) crystals,we achieve an overall energy resolution better than 35 meV full width at half maximum (FWHM) at the Ru L$_3$-edge, in excellent agreement with ray tracing simulations