Design of soft X-ray grating having enhanced diffraction efficiency for detecting trace born at 183 eV

Koike, Masato; Imazono, Takashi; Nagano, Tetsuya*; Koeda, Masaru*; Sasai, Hiroyuki*; Oue, Yuki*; Yonezawa, Zeno*; Kuramoto, Satoshi*; Terauchi, Masami*; Takahashi, Hideyuki*; Handa, Nobuo*; Murano, Takanori*

Knowledge of the state density of a combination electron directing the properties of material is provided by soft X-ray emission spectrum. Particularly, boron (B-K: 183.3 eV) is key material as a trace element in steel materials, and there is a strong demand for a very small amount of born measurement from the industry. In this study, we designed new laminar-type diffraction gratings and performed theoretical evaluation. The surface is over-coated by a carbon layer on the surface of the conventional Au coated grating. As the base grating a grating of groove density of 1200 lines/mm, groove depth of 16nm, duty ratio of 0.3, and Au coating of 30 nm are assumed. The incidence angle and spectral order are 87.0 and +1, respectively. A grating coated with C on the base grating shows approximately 1.4-2 times higher diffraction efficiency comparing with the base grating at 183.3 eV.