Toyoshima Akio, Kikuchi Takashi, Tanaka Hirokazu, Mase Kazuhiko, Amemiya Kenta
Institute of Materials Structure Science, KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan.
J Synchrotron Radiat. 2015 Nov;22(6):1359-63. doi: 10.1107/S1600577515015040. Epub 2015 Sep 26.
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.
无碳镀铬光学元件在碳 K 边区域（280 - 330 电子伏特）是理想的，因为一阶光的反射率大于镀金光学元件，而二阶谐波（560 - 660 电子伏特）被铬 L 边和氧 K 边吸收显著抑制。在此，日本筑波光子工厂的真空紫外和软 X 射线分支光束线 BL - 13B 采用了镀铬、镀金和镀镍的镜子。在未单色化的同步辐射照射下，将镀铬镜暴露于 8×10⁻² 帕的氧气中 1 小时，几乎完全去除了镀铬镜上的碳污染。几小时内，腔室内的压力恢复到 10⁻⁷ 帕量级。发现在碳 K 边区域（560 - 660 电子伏特），镀铬镜的二阶谐波反射率比镀金镜小 0.1 - 0.48 倍。
