The road to ultrahigh-resolution X-ray spectrometers

Two recent developments at the Advanced Photon Source explore paths to routine use of sub-meV x-rays to probe low-energy excitations in matter. The first is a remarkable experimental demonstration of an x-ray optical scheme that produces x-ray beams with sub-meV linewidths (FWHM) and elimination of the normal Lorentzian tails

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The road to ultrahigh-resolution X-ray spectrometers