학술논문
A new benchmark of soft X-ray transition energies of Ne, CO$_2$, and SF$_6$: paving a pathway towards ppm accuracy
Document Type
Working Paper
Author
Stierhof, J.; Kühn, S.; Winter, M.; Micke, P.; Steinbrügge, R.; Shah, C.; Hell, N.; Bissinger, M.; Hirsch, M.; Ballhausen, R.; Lang, M.; Gräfe, C.; Wipf, S.; Cumbee, R.; Betancourt-Martinez, G. L.; Park, S.; Niskanen, J.; Chung, M.; Porter, F. S.; Stöhlker, T.; Pfeifer, T.; Brown, G. V.; Bernitt, S.; Hansmann, P.; Wilms, J.; López-Urrutia, J. R. Crespo; Leutenegger, M. A.
Source
Subject
Language
Abstract
A key requirement for the correct interpretation of high-resolution X-ray spectra is that transition energies are known with high accuracy and precision. We investigate the K-shell features of Ne, CO$_2$, and SF$_6$ gases, by measuring their photo ion-yield spectra at the BESSY II synchrotron facility simultaneously with the 1s-np fluorescence emission of He-like ions produced in the Polar-X EBIT. Accurate ab initio calculations of transitions in these ions provide the basis of the calibration. While the CO$_2$ result agrees well with previous measurements, the SF$_6$ spectrum appears shifted by ~0.5 eV, about twice the uncertainty of the earlier results. Our result for Ne shows a large departure from earlier results, but may suffer from larger systematic effects than our other measurements. The molecular spectra agree well with our results of time-dependent density functional theory. We find that the statistical uncertainty allows calibrations in the desired range of 1-10 meV, however, systematic contributions still limit the uncertainty to ~40-100 meV, mainly due to the temporal stability of the monochromator energy scale. Combining our absolute calibration technique with a relative energy calibration technique such as photoelectron energy spectroscopy will be necessary to realize its full potential of achieving uncertainties as low as 1-10 meV.
Comment: 13 pages, 7 figures
Comment: 13 pages, 7 figures