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Title: Soft x-ray optical constants of sputtered chromium thin films with improved accuracy in the L and M absorption edge regions

Journal Article · · Journal of Applied Physics
DOI: https://doi.org/10.1063/1.5027488 · OSTI ID:1482536
 [1];  [2];  [2];  [3];  [4];  [5];  [5]; ORCiD logo [6];  [6];  [2]
  1. Universite Paris-Saclay (France). Laboratoire Charles Fabry, Institut d'Optique Graduate School, CNRS; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Center for X-ray Optics
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Center for X-ray Optics
  3. Universite Paris-Saclay (France). Laboratoire Charles Fabry, Institut d'Optique Graduate School, CNRS; Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  5. Universite Paris-Saclay (France). Laboratoire Charles Fabry, Institut d'Optique Graduate School, CNRS
  6. Institut des NanoSciences de Paris (France)
+ Show Author Affiliations

In this paper, we determine with improved accuracy the complex index of refraction n = 1 - δ + iβ of sputtered chromium thin films for photon energies ranging from 25 eV to 813 eV. These data include the first absolute measurements of the absorption fine structure near the Cr-L edge. First, we verified by combining Rutherford Backscattering Spectrometry and grazing-incidence x-ray reflectometry that the sputtered thin films were pure Cr with a density consistent with tabulated values. Then, we demonstrated that the Cr surface oxide layer remains stable when the samples are exposed to air for up to 4 years. The Cr absorption coefficient β was determined from the transmittance of freestanding Cr thin films with various thicknesses, measured at the ALS synchrotron radiation source. A model is proposed to correct the transmittance data from the spectral contamination of the source. Finally, we used the new β values, combined with theoretical and tabulated data from the literature, in order to calculate the δ values by the Kramers-Kronig relation. The improvement in the accuracy of β values is demonstrated by the f-sum rule. Finally, an additional validation of the new Cr optical constants (δ, β) is performed by comparing the simulated and experimental reflectance of a Cr/B4C multilayer mirror near the Cr-L2,3 edge.

Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC); USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
AC02-05CH11231; AC52-07NA27344
OSTI ID:
1482536
Alternate ID(s):
OSTI ID: 1527275
Report Number(s):
LLNL-JRNL-768637; ark:/13030/qt0b28x4nt
Journal Information:
Journal of Applied Physics, Vol. 124, Issue 3; ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 13 works
Citation information provided by
Web of Science

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Cited By (2)

Optical constants of magnetron sputtered Pt thin films with improved accuracy in the N- and O-electronic shell absorption regions journal February 2019
Optical constants of sputtered beryllium thin films determined from photoabsorption measurements in the spectral range 20.4–250 eV journal January 2020

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