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Title: Enhancement of diffraction efficiency of laminar-type diffraction gratings overcoated with diamond-like carbon (DLC) in soft x-ray region

Abstract

Boron is the critical trace element in the production of high quality steel, creating a great demand for an efficient detection method of the B-K emission band at around 6.76 nm. To meet this demand we made a simulation study and obtained a practical method to improve the diffraction efficiency of metal-coated laminar-type gratings for a grazing incidence flat-field spectrograph by overcoating a sufficiently transparent high-density material. In the simulation the diffraction efficiency in a spectral region of 3.5-8.5 nm was computed for several combinations of overcoating materials and coating metals, with various thicknesses of the overcoating layer. The result obtained are: (1) the best overcoating material is high-density diamond-like carbon (DLC) having a density of 3.1 g/cm{sup 3}, (2) its optimum thickness is 24 nm at an angle of incidence of 87.0°, and (3) with this thickness the first-order diffraction efficiency is expected to reach 29.7 %, which well exceeds 15.6 % for Ni-coated (or 14.1 % for Au-coated) grating.

Authors:
;  [1]; ; ; ; ;  [2];  [3];  [4]; ;  [5]
  1. Quantum Beam Science Center, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215 Japan (Japan)
  2. Device Dept., Shimadzu Corp., 1Nishinokyo-Kuwabara-cho, Nakagyo-ku, Kyoto 604-8511 Japan (Japan)
  3. Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 Japan (Japan)
  4. Science Equipment Sales Dept., JEOL Ltd., 2-1-1 Ohtemachi, Chiyoda-ku, Tokyo 100-0004 Japan (Japan)
  5. SA Business Unit, JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558 Japan (Japan)
Publication Date:
OSTI Identifier:
22608427
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1741; Journal Issue: 1; Conference: SRI2015: 12. international conference on synchrotron radiation instrumentation, New York, NY (United States), 6-10 Jul 2015; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; BORON; DETECTION; DIAMONDS; DIFFRACTION; DIFFRACTION GRATINGS; EFFICIENCY; EMISSION; INCIDENCE ANGLE; LAYERS; METALS; SIMULATION; SOFT X RADIATION; STEELS; THICKNESS

Citation Formats

Koike, Masato, E-mail: koike.masato@jaea.go.jp, Imazono, Takashi, Nagano, Tetsuya, Sasai, Hiroyuki, Oue, Yuki, Yonezawa, Zeno, Kuramoto, Satoshi, Terauchi, Masami, Takahashi, Hideyuki, Notoya, Satoshi, and Murano, Takanori. Enhancement of diffraction efficiency of laminar-type diffraction gratings overcoated with diamond-like carbon (DLC) in soft x-ray region. United States: N. p., 2016. Web. doi:10.1063/1.4952917.
Koike, Masato, E-mail: koike.masato@jaea.go.jp, Imazono, Takashi, Nagano, Tetsuya, Sasai, Hiroyuki, Oue, Yuki, Yonezawa, Zeno, Kuramoto, Satoshi, Terauchi, Masami, Takahashi, Hideyuki, Notoya, Satoshi, & Murano, Takanori. Enhancement of diffraction efficiency of laminar-type diffraction gratings overcoated with diamond-like carbon (DLC) in soft x-ray region. United States. doi:10.1063/1.4952917.
Koike, Masato, E-mail: koike.masato@jaea.go.jp, Imazono, Takashi, Nagano, Tetsuya, Sasai, Hiroyuki, Oue, Yuki, Yonezawa, Zeno, Kuramoto, Satoshi, Terauchi, Masami, Takahashi, Hideyuki, Notoya, Satoshi, and Murano, Takanori. Wed . "Enhancement of diffraction efficiency of laminar-type diffraction gratings overcoated with diamond-like carbon (DLC) in soft x-ray region". United States. doi:10.1063/1.4952917.
@article{osti_22608427,
title = {Enhancement of diffraction efficiency of laminar-type diffraction gratings overcoated with diamond-like carbon (DLC) in soft x-ray region},
author = {Koike, Masato, E-mail: koike.masato@jaea.go.jp and Imazono, Takashi and Nagano, Tetsuya and Sasai, Hiroyuki and Oue, Yuki and Yonezawa, Zeno and Kuramoto, Satoshi and Terauchi, Masami and Takahashi, Hideyuki and Notoya, Satoshi and Murano, Takanori},
abstractNote = {Boron is the critical trace element in the production of high quality steel, creating a great demand for an efficient detection method of the B-K emission band at around 6.76 nm. To meet this demand we made a simulation study and obtained a practical method to improve the diffraction efficiency of metal-coated laminar-type gratings for a grazing incidence flat-field spectrograph by overcoating a sufficiently transparent high-density material. In the simulation the diffraction efficiency in a spectral region of 3.5-8.5 nm was computed for several combinations of overcoating materials and coating metals, with various thicknesses of the overcoating layer. The result obtained are: (1) the best overcoating material is high-density diamond-like carbon (DLC) having a density of 3.1 g/cm{sup 3}, (2) its optimum thickness is 24 nm at an angle of incidence of 87.0°, and (3) with this thickness the first-order diffraction efficiency is expected to reach 29.7 %, which well exceeds 15.6 % for Ni-coated (or 14.1 % for Au-coated) grating.},
doi = {10.1063/1.4952917},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1741,
place = {United States},
year = {Wed Jul 27 00:00:00 EDT 2016},
month = {Wed Jul 27 00:00:00 EDT 2016}
}
  • Efficiently detecting the B-K emission band around 6.76 nm from a trace concentration of boron in steel compounds has motivated a theoretical exploration of means of increasing the diffraction efficiency of a laminar grating with carbon overcoating. To experimentally evaluate this enhancement, a Ni grating was coated with a high-density carbon film, i.e., diamond-like carbon (DLC). The first order diffraction efficiencies of the Ni gratings coated with and without DLC were measured to be 25.8 % and 16.9 %, respectively, at a wavelength of 6.76 nm and an angle of incidence of 87.07°. The ratio of diffraction efficiency obtained experimentallymore » vs. that calculated by numerical simulation is 0.87 for the DLC-coated Ni grating. The diffraction efficiency of a Ni grating coated with a low-density carbon film, amorphous carbon (a-C), was also slightly improved to be 19.6 %. Furthermore, a distinct minimum of the zeroth order lights of the two carbon-coated Ni gratings were observed at around 6.76 nm, which is coincident with the maximum of the first order light.« less
  • We report on measurements of the diffraction efficiency of 200-nm-period freestanding blazed transmission gratings for wavelengths in the 0.96 to 19.4 nm range. These critical-angle transmission (CAT) gratings achieve highly efficient blazing over a broad band via total external reflection off the sidewalls of smooth, tens of nanometer thin ultrahigh aspect-ratio silicon grating bars and thus combine the advantages of blazed x-ray reflection gratings with those of more conventional x-ray transmission gratings. Prototype gratings with maximum depths of 3.2 and 6 {mu}m were investigated at two different blaze angles. In these initial CAT gratings the grating bars are monolithically connectedmore » to a cross support mesh that only leaves less than half of the grating area unobstructed. Because of our initial fabrication approach, the support mesh bars feature a strongly trapezoidal cross section that leads to varying CAT grating depths and partial absorption of diffracted orders. While theory predicts broadband absolute diffraction efficiencies as high as 60% for ideal CAT gratings without a support mesh, experimental results show efficiencies in the range of {approx}50-100% of theoretical predictions when taking the effects of the support mesh into account. Future minimization of the support mesh therefore promises broadband CAT grating absolute diffraction efficiencies of 50% or higher.« less
  • High-frequency multilayer-coated blazed diffraction gratings (HFMBGs) are most promising elements for ultrahigh resolution soft x-ray spectroscopy. As it has been demonstrated recently [Voronov et al., Opt. Express 23, 4771 (2015)], the efficiency limit for in-plane diffraction can exceed 2–3 times, in higher orders too, when the period of a HFMBG is shorter than an attenuation length for soft x-rays and a bilayer asymmetry is designed. In this letter, using numerical experiments based on the rigorous electromagnetic theory, a possibility of off-plane diffraction and symmetrical multilayer coatings to enhance the efficiency of soft-x-ray high-order HFMBGs very closely to the absolute limit,more » i.e., 0.92–0.98 of the reflectance of the respective W/B4C multilayer, has been demonstrated.« less
  • W/C and Co/SiO2 multilayer gratings have been fabricated by depositing a multilayer coating on the surface of laminar-type holographic master gratings. The diffraction efficiency was measured by reflectometers in the energy region of 0.6-8.0 keV at synchrotron radiation facilities as well as with an x-ray diffractometer at 8.05 keV. The Co/SiO2 and W/C multilayer gratings showed peak diffraction efficiencies of 0.47 and 0.38 at 6.0 and 8.0 keV, respectively. To our knowledge, the peak efficiency of the W/C multilayer grating is the highest measured with hard x rays. The diffraction efficiency of the Co/SiO2 multilayer gratings was higher than thatmore » of the W/C multilayer grating in the energy range of 2.5-6.0 keV. However, it decreased significantly in the energy above the K absorption edge of Co(7.71 keV). For the Co/SiO2 multilayer grating, the measured diffraction efficiencies agreed with the calculated curves assuming a rms roughness of?1 nm.« less
  • A multilayer laminar-type holographic grating having an average groove density of2400 lines/mmis designed and fabricated for use with a soft-x-ray flat-field spectrograph covering the0.70-0.75 nm region. A varied-line-spaced groove pattern is generated by the use of an aspheric wavefront recording system, and laminar-type grooves are formed by a reactive ion-etching method.Mo/SiO2 multilayers optimized for the emission lines of Hf-M,Si-K, and W-M are deposited on one of the three designated areas on the grating surface in tandem. The measured first-order diffraction efficiencies at the respective centers of the areas are 18%-20%. The flat-field spectrograph equipped with the grating indicates a spectralmore » linewidth of8-14 eV for the emission spectra generated from electron-impact x-ray sources.« less