Open AccessIn situ removal of carbon contamination from a chromium‐coated mirror: ideal optics to suppress higher‐order harmonics in the carbon K ‐edge region
Author(s) -
Toyoshima Akio,
Kikuchi Takashi,
Tanaka Hirokazu,
Mase Kazuhiko,
Amemiya Kenta
Publication year - 2015
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s1600577515015040
Subject(s) - chromium , carbon fibers , harmonics , materials science , synchrotron radiation , optics , absorption edge , extreme ultraviolet , irradiation , beamline , nickel , analytical chemistry (journal) , physics , optoelectronics , chemistry , laser , metallurgy , composite material , chromatography , quantum mechanics , voltage , band gap , composite number , nuclear physics , beam (structure)
Carbon‐free chromium‐coated optics are ideal in the carbon K ‐edge region (280–330 eV) because the reflectivity of first‐order light is larger than that of gold‐coated optics while the second‐order harmonics (560–660 eV) are significantly suppressed by chromium L ‐edge and oxygen K ‐edge absorption. Here, chromium‐, gold‐ and nickel‐coated mirrors have been adopted in the vacuum ultraviolet and soft X‐ray branch beamline BL‐13B at the Photon Factory in Tsukuba, Japan. Carbon contamination on the chromium‐coated mirror was almost completely removed by exposure to oxygen at a pressure of 8 × 10 −2 Pa for 1 h under irradiation of non‐monochromated synchrotron radiation. The pressure in the chamber recovered to the order of 10 −7 Pa within a few hours. The reflectivity of the chromium‐coated mirror of the second‐order harmonics in the carbon K ‐edge region (560–660 eV) was found to be a factor of 0.1–0.48 smaller than that of the gold‐coated mirror.