Back to Blog
Spectrometer grating dispersio7/5/2023 ![]() However, to become competitive with inelastic neutron scattering, the resolution of the RIXS spectrometers must be improved by more than an order of magnitude. ![]() A RIXS spectrometer at NSLS-II has been designed to achieve a spectral resolution of Δ E ≃ 15 meV and resolving power E/ Δ E ≃ 6.6 × 10 4 (Dvorak et al., 2016 ). Various facilities, such as ALS (Warwick et al., 2014 Chuang et al., 2017 ), TLS (Lai et al., 2014 ), DLS (Zhou, 2019 ), MAX IV, European XFEL, and LCLS-II are now constructing new soft RIXS beamlines and spectrometers, aiming to achieve higher throughput and higher resolution. This breakthrough became possible because of rapid improvements in the spectral resolution Δ E of RIXS spectrometers at synchrotron radiation facilities worldwide, initially from Δ E ≃ 120 meV (Ghiringhelli et al., 2006 Strocov et al., 2010 ), achieved at SLS in 2006 to recently demonstrated resolutions of Δ E ≃ 40 meV at ESRF (Chaix et al., 2017 Brookes et al., 2018 ) and Δ E ≃ 20 meV at NSLS-II (Bisogni, 2019 ). RIXS studies in the soft X-ray domain recently increased tremendously in importance because researchers discovered that it is possible to observe and study orbital and magnetic excitations in addition to charge and lattice collective excitations in condensed matter, notably in high- T c superconductors (Braicovich et al., 2010 Tacon et al., 2011 Schlappa et al., 2012 Dean et al., 2013 ) previously accessible only by neutrons. They are key optical elements of resonant inelastic X-ray scattering (RIXS) spectrometers. Diffraction gratings are typically not practical at photon energies E above 2 keV, but they are still very useful at lower photon energies in the soft X-ray domain, 0.2 keV ≲ E ≲ 2 keV. The shorter the radiation wavelength, the more challenging it is to manufacture efficient diffraction gratings. They are essential for optical instruments that operate in a very broad spectral range from infrared to soft X-ray domains. Examples of large-dispersion-rate crystal diffraction gratings operating near the 930 eV L 3 absorption edge in Cu and of the 2.838 keV L 3-edge in Ru are presented.ĭiffraction gratings are the most common type of light-dispersing optical elements. ![]() This opens new opportunities to design and implement soft X-ray resonant inelastic scattering (RIXS) spectrometers with spectral resolutions that are up to two orders of magnitude higher than what is currently possible, to further advance a very dynamic field of RIXS spectroscopy, and to make it competitive with inelastic neutron scattering. Here it is shown that crystals in non-coplanar asymmetric X-ray Bragg diffraction can function as high-reflectance broadband soft X-ray diffraction gratings with dispersion rates that are at least two orders of magnitude larger than those that are possible with state-of-the-art man-made gratings. The greatest challenge is of course to achieve large dispersion rates in the short-wavelength X-ray domain. Diffraction gratings with large angular dispersion rates are central to obtaining high spectral resolution in grating spectrometers operating over a broad spectral range from infrared to soft X-ray domains. ![]()
0 Comments
Read More
Leave a Reply. |