• Yin, Z.; Löchel, H.; Rehanek, J.; Goy, C.; Kalinin, A.; Schottelius, A.; Trinter, F.; Miedema, P.; Jain, A.; Valerio, J.; Busse, P.; Lehmkühler, F.; Möller, J.; Grübel, G.; Madsen, A.; Viefhaus, J.; Grisenti, R.; Beye, M.; Erko, A.; Techert, S.: X-ray spectroscopy with variable line spacing based on reflection zone plate optics. Optics Letters 43 (2018), p. 4390-4393

10.1364/OL.43.004390
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Abstract:
X-ray spectroscopy is a method, ideally suited for investigating the electronic structure of matter, which has been enabled by the rapid developments in light sources and instruments. The x-ray fluorescence lines of life-relevant elements such as carbon, nitrogen, and oxygen are located in the soft x-ray regime and call for suitable spectrometer devices. In this Letter, we present a high-resolution spectrum of liquid water, recorded with a soft x-ray spectrometer based on a reflection zone plate (RZP) design. The RZP-based spectrometer with meridional variation of line space density from 2953 to 3757 l/mm offers extremely high detection efficiency and, at the same time, medium energy resolution. We can reproduce the well-known splitting of liquid water in the lone pair regime with 10 s acquisition time.