Measurement of the O2O3O4 and O3O4O5 Super Coster-Kronig Rates in Tungsten via Asymmetric Diffraction Spectrometry

The tungsten Lγ transitions between 11 and 12 keV and Kα transitions from 57 to 60 keV were produced by a laboratory electron-bombarded x-ray source and simultaneously recorded with high resolution by using multiple diffraction planes of the same quartz crystal operating in Cauchois transmission geometry. The W Kα transitions were dispersed by the (5 0 2) planes, which were perpendicular to the crystal entrance surface, and by the (6 0 2), (7 0 2), and (8 0 4) planes which were rotated with respect to the (5 0 2) planes by angles up to 4.80°. The W Lγ transitions were dispersed by the (2 0 1) planes rotated from the (5 0 2) planes by 4.01°. The spectra from the five planes were simultaneously recorded on image plate detectors, and spectra were also recorded by scanning solid-state electronic detectors with narrow slits across the spectral lines. The metrology of the L and K shell spectra diffracted from multiple quartz planes enabled the detailed analysis of the detector spatial resolution and accurate measurement of the instrumental broadening produced by the various quartz diffraction planes. The W Lγ spectra had the highest instrumental resolving power, 1800, permitting for the first time the resolution of the blended Lγ4' (L1O2) and Lγ4 (L1O3) transitions. After subtracting the instrumental and detector contributions to the line widths, the remainder was assigned to the natural line widths. The measured widths of the O2 and O3 levels were 2.9 eV and 1.9 eV, respectively, and based on atomic code calculations these widths are attributed to the O2O3O4 and O3O4O5 super Coster–Kronig processes. This work demonstrates the ability to simultaneously record high resolution (<1 eV) L and K spectra to determine the line shapes of the heavy elements (e.g. W through Am) by using multiple planes of a single quartz crystal and to accurately measure the non-radiative super Coster–Kronig rates which are closely related to the energy level structure of the outer shells of the heavy elements.