19 July 1996 Iridium optical constants from x-ray transmission measurements over 2 to 12 keV
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Precise transmission measurements of free standing iridium foils and of iridium coatings supported on thin polyimide film have been made at the X8 beamline of the National Synchrotron Light Source, at energies from 2 to 12 keV. These measurements were conducted to provide iridium optical constants in support of NASA's Advanced X-ray Astrophysics Facility (AXAF). Transmission data were collected at small energy increments across iridium M and L absorption edges to study detailed edge structures. From these data, the imaginary components of the index of refraction were computed. The data also allows computation of the real parts, using the Kramers-Kronig dispersion integral. Preliminary results indicate a measurement accuracy of better than one percent for transmission. Absorption coefficients deviate by varying amounts from values predicted from Henke data table, which is consistent with the accuracy claimed for those table.s Nonuniform thickness in our iridium foils may be a source of errors in our analysis and improved foils are being sought. Additional measurements will also be needed with foils of different thickness to account and correct for possible effects of sample thickness on the determination of absorption edge fine structure. To our knowledge, transmission measurements of this degree of accuracy and precision have not been previously reported in the literature for iridium in the 2- 12 keV energy range.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Bernard Harris, Bernard Harris, Dale E. Graessle, Dale E. Graessle, Jonathan J. Fitch, Jonathan J. Fitch, Jiahong Zhang Juda, Jiahong Zhang Juda, Richard L. Blake, Richard L. Blake, Mark L. Schattenburg, Mark L. Schattenburg, Eric M. Gullikson, Eric M. Gullikson, } "Iridium optical constants from x-ray transmission measurements over 2 to 12 keV", Proc. SPIE 2805, Multilayer and Grazing Incidence X-Ray/EUV Optics III, (19 July 1996); doi: 10.1117/12.245109; https://doi.org/10.1117/12.245109


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