Keywords

uranium oxide, reflective coating, refraction, film reflectors

Abstract

We present the measured reflectances (Beamline 6.3.2, ALS and LBNL) of naturally oxidized uranium and naturally oxidized nickel thin films from 100-460 eV (2.7 to 11.6 nm) at 5 and 15 degrees grazing incidence. These show that uranium as UO2, can fulfill its promise as the highest known single surface reflector for this portion of the soft x-ray region, being nearly twice as reflective as nickel in the 124-250 eV (5-10 nm) region. This is due to its large index of refraction coupled with low absorption. Nickel is commonly used in soft x-ray applications in astronomy and synchrotrons. (Its reflectance at 10° exceeds that of Au and Ir for most of this range.) We prepared uranium and nickel thin films via DC-magnetron sputtering of depleted U target and resistive heating evaporation respectively. Ambient oxidation quickly brought the U sample to UO2 (total thickness of 30 nm). The nickel sample (50 nm) also acquired a thin native oxide coating (<2 >nm). Though the density of U in UO2 is only half of the metal, its reflectance is high and it is relatively stable against further changes.

Original Publication Citation

Richard L. Sandberg, David D. Allred, Luke J. Bissell, Jed E. Johnson, R. Steven Turley, "Uranium Oxide as a Highly Reflective Coating from 1-4 eV," in Synchrotron Radiation Instrumentation: Eighth International Conference on Synchrotron Radiation Instrumentation, San Francisco, California, 25-29 August 23, AIP presentation proceedings, ISSN: 94-243X v. 75, edited by Tony Warwick, et al. (American Institute of Physics, Melville, N.Y., 24) pp. 796-799. [http://proceedings.aip.org/resource/2/apcpcs/75/1/796_1][http://dx.doi.org/1.163/1.1757916].