Comparative study of the X-ray reflectivity and in-depth profile of a-C, B₄C and Ni coatings at 0.1-2 keV.
The use of soft X-rays near the carbon edge of absorption (270-300 eV) greatly enhances studies in various branches of science. However, the choice of reflecting coatings for mirrors operating in free-electron and X-ray free-electron laser (FEL and XFEL) beamlines in this spectral range is not so evident and experimental justifications of the mirror efficiency are rather limited. In the present paper it is demonstrated experimentally that the reflectivity of B4C- and Ni-coated grazing-incidence mirrors is high enough for their operation in FEL or XFEL beamlines near the carbon K-edge of absorption. The minimal reflectivity of both mirrors proves to exceed 80% near the carbon absorption edge at a grazing angle of 0.6°. An in-depth profile of the chemical elements composing the reflecting coatings is reconstructed based on analysis of a set of reflectivity curves measured versus the grazing angle at different photon energies in the soft X-ray spectral region. This allows us to predict correctly the mirror reflectivity at any X-ray energy and any grazing angle.
Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky Prospect 59, Moscow 119333, Russian Federation.
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IV
Kozhevnikov
St Petersburg State University, Ulyanovskaya 3, Peterhof, St Petersburg 198504, Russian Federation.
E O
EO
Filatova
St Petersburg State University, Ulyanovskaya 3, Peterhof, St Petersburg 198504, Russian Federation.
A A
AA
Sokolov
St Petersburg State University, Ulyanovskaya 3, Peterhof, St Petersburg 198504, Russian Federation.
A S
AS
Konashuk
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert Einstein Strasse 15, 12489 Berlin, Germany.
F
F
Siewert
Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Strasse 1, 21502 Geesthacht, Germany.
M
M
Störmer
Université Bordeaux 1, CEA, CNRS, CELIA, 351 Cours de la Libération, 33405 Talence, France.
J
J
Gaudin
DESY, Notkestrasse 85, 22607 Hamburg, Germany.
B
B
Keitel
European XFEL GmbH, Albert Einstein Ring 19, 22761 Hamburg, Germany.
L
L
Samoylova
European XFEL GmbH, Albert Einstein Ring 19, 22761 Hamburg, Germany.
H
H
Sinn
XFEL mirrors; in-depth profile; inverse problem; soft X-ray optics