scholarly journals The Astro-E Mission

1998 ◽  
Vol 188 ◽  
pp. 75-78 ◽  
Author(s):  
Y. Ogawara
Keyword(s):  
High Sensitivity ◽  
High Energy ◽  
High Energy Resolution ◽  
High Energy Astrophysics ◽  
X Ray ◽  
The Past ◽  
Broad Energy Range ◽  
Indispensable Tool ◽  
Year 2000 ◽  
Broad Energy

The past three decades have seen an explosion in high-energy astrophysics. We have found X-ray astronomy to be an indispensable tool in understanding our Universe. The discipline has become mature, and future X-ray observatories must be more highly specialized. High-resolution spectroscopic imaging in the band above 2 keV, systematically exploited by ASCA, has led to much new astrophysical knowledge. ASCA has also been playing a particularly important role in studying sources hidden behind dense material. Astro-E, the successor of ASCA, is scheduled for launch in the year 2000 by the Institute of Space and Astronautical Science (ISAS) with its newly developed M-V rocket (Ogawara & Inoue 1997). Our new Astro-E observatory features high energy resolution and high sensitivity over the broad energy range 0.5 keV to 600 keV. The general emphasis of the observatory is to provide large collecting areas at higher energies, with angular resolution good enough to avoid the confusion limit. This paper provides a brief description of the performance of the Astro-E instruments.

Local atomic structure analysis around Mg atom doped in GaN by X-ray absorption spectroscopy and spectrum simulations

2021 ◽  
Vol 28 (4) ◽  
Author(s):  
Noritake Isomura ◽  
Yasuji Kimoto
Keyword(s):  
Absorption Spectroscopy ◽  
Density Functional ◽  
High Sensitivity ◽  
High Energy ◽  
High Energy Resolution ◽  
Array Detector ◽  
Superconducting Tunnel Junction ◽  
Substitutional Site ◽  
X Ray ◽  
X Ray Absorption

The identification of the incorporated site of magnesium (Mg) and hydrogen (H) required for p-type formation in gallium nitride (GaN) power devices has been demonstrated by X-ray absorption spectroscopy (XAS). In this study, the fluorescence line of Mg with 3 × 1019 atoms cm−3 was successfully separated from that of Ga using a superconducting tunnel junction array detector with high sensitivity and high energy resolution, and consequently the Mg K-edge XAS spectra of such dilute samples were obtained. The site of Mg atoms incorporated into the GaN lattice was identified as the Ga substitutional site by comparing the experimental XAS spectrum with the simulated spectra calculated by density functional theory. In addition, the presence or absence of H around Mg can be determined through distinctive characteristics expected from the spectrum simulations.

Elektronen-Energie-Verlust-Spektroskopische Untersuchungen an Luftfiltern zur Bewertung der Luftqualität / Electron-Energy-Loss-Spectroscopical Investigations on Air Filters for the Analysis of the Air Quality

1988 ◽  
Vol 43 (3-4) ◽  
pp. 155-161 ◽  
Author(s):  
Bernhard Wolf
Keyword(s):  
Air Quality ◽  
Energy Loss ◽  
Electron Energy ◽  
High Sensitivity ◽  
High Energy ◽  
High Energy Resolution ◽  
X Ray ◽  
Simple Arrangement ◽  
Wet Chemical ◽  
Electron Energy Loss

In trace analysis it is more and more attempted to replace wet-chemical detection procedures by methods which allow a quantitative analysis without any material disintegration, but on exploiting the characteristic physical properties of the components searched for. Based on a procedure for physical and biological valuation of the air quality by means of X-ray microanalysis (WDX/EDX), a procedure which was previously developed by our group, we deepened our investigations by the help of electron-energy-loss-spectroscopy (EELS). The combination of that procedure with EELS proved to be very advantageous as it revealed a high sensitivity as well as a high energy resolution. The main advantages are to be found in the simple arrangement of the sample detector and in the fact, not only being able to examine deposits microscopically, but also to analyze them chemically without disintegrating the material. Thus loss of material and denaturation are largely excluded.

scholarly journals THE ASTRO-H MISSION

2013 ◽  
Vol 53 (A) ◽  
pp. 803-806
Author(s):  
Yoshitomo Maeda ◽  
Tadayuki Takahashi ◽  
Kazuhisa Mitsuda ◽  
Richard Kelley
Keyword(s):  
Spectral Resolution ◽  
High Sensitivity ◽  
High Energy ◽  
The Other ◽  
High Spectral Resolution ◽  
High Energy Astrophysics ◽  
Extended Source ◽  
X Ray ◽  
Imaging Capability ◽  
Wide Energy

A review of the Astro-H mission is presented here on behalf of the Astro-H collaboration. The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). One of the main uniquenesses of the ASTRO-H satellite is the high sensitivity and imaging capability of the wide energy band from 0.3 keV to 600 keV. The coverage is achieved by combining the four instruments of the SXS, SXI, HXI, and SGD. The other main uniqueness is a spectroscopic capability not only for a point-like source but also for an extended source with high spectral resolution of Δ<em>E</em>~4÷7eV of SXS. Using the unique powers of these instruments, ASTRO-H will address unresolved issues in high-energy astrophysics.

Use of Polycapillary Optics to Increase the Effective Area of Microcalorimeter Spectrometers

1997 ◽  
Vol 3 (S2) ◽  
pp. 1075-1076 ◽  
Author(s):  
D. A. Wollman ◽  
Christopher Jezewski ◽  
G. C. Hilton ◽  
Qi-Fan Xiao ◽  
K. D. Irwin ◽  
...  
Keyword(s):  
Energy Resolution ◽  
Count Rate ◽  
Small Area ◽  
Solid Angle ◽  
Collection Efficiency ◽  
High Energy ◽  
High Energy Resolution ◽  
X Rays ◽  
X Ray ◽  
Broad Energy Range

Although the performance of high-energy-resolution microcalorimeter spectrometers for x-ray microanalysis is encouraging, the future widespread acceptance of these spectrometers as valuable microanalysis instruments depends on improvements in both achievable count rate and geometrical x-ray collection efficiency. While the maximum output count rate of our microcalorimeter (∼160 s−1) is much less than that of conventional EDS detectors operating at their highest energy resolution (∼3000 s−1), we are confident that we can significantly improve the count rate without loss of energy resolution (∼10 eV FWHM over a broad energy range). Increasing the area (and thus solid angle) of the microcalorimeter is a more difficult problem, however, as the best microcalorimeter performance is achieved using small-area (typically 250 μm by 250 μm) absorbers with low heat capacity.This problem can be solved by using an x-ray lens to increase the collection efficiency of the microcalorimeter spectrometer. A polycapillary optic consisting of tens of thousands of fused capillaries can collect x-rays from a point x-ray source over a large solid angle and focus the x-rays onto the small-area absorber of the microcalorimeter.

scholarly journals High-Energy-Resolution Fluorescence-Detected X-ray Absorption of the Q Intermediate of Soluble Methane Monooxygenase

2017 ◽  
Vol 139 (49) ◽  
pp. 18024-18033 ◽  
Author(s):  
Rebeca G. Castillo ◽  
Rahul Banerjee ◽  
Caleb J. Allpress ◽  
Gregory T. Rohde ◽  
Eckhard Bill ◽  
...  
Keyword(s):  
Energy Resolution ◽  
Methane Monooxygenase ◽  
High Energy ◽  
High Energy Resolution ◽  
X Ray ◽  
Soluble Methane Monooxygenase ◽  
X Ray Absorption

scholarly journals High-energy resolution X-ray absorption and emission spectroscopy reveals insight into unique selectivity of La-based nanoparticles for CO2

2015 ◽  
Vol 112 (52) ◽  
pp. 15803-15808 ◽  
Author(s):  
Ofer Hirsch ◽  
Kristina O. Kvashnina ◽  
Li Luo ◽  
Martin J. Süess ◽  
Pieter Glatzel ◽  
...  
Keyword(s):  
Energy Resolution ◽  
Emission Spectroscopy ◽  
High Energy ◽  
Unit Cell ◽  
High Energy Resolution ◽  
Electron Configuration ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

The lanthanum-based materials, due to their layered structure and f-electron configuration, are relevant for electrochemical application. Particularly, La2O2CO3 shows a prominent chemoresistive response to CO2. However, surprisingly less is known about its atomic and electronic structure and electrochemically significant sites and therefore, its structure–functions relationships have yet to be established. Here we determine the position of the different constituents within the unit cell of monoclinic La2O2CO3 and use this information to interpret in situ high-energy resolution fluorescence-detected (HERFD) X-ray absorption near-edge structure (XANES) and valence-to-core X-ray emission spectroscopy (vtc XES). Compared with La(OH)3 or previously known hexagonal La2O2CO3 structures, La in the monoclinic unit cell has a much lower number of neighboring oxygen atoms, which is manifested in the whiteline broadening in XANES spectra. Such a superior sensitivity to subtle changes is given by HERFD method, which is essential for in situ studying of the interaction with CO2. Here, we study La2O2CO3-based sensors in real operando conditions at 250 °C in the presence of oxygen and water vapors. We identify that the distribution of unoccupied La d-states and occupied O p- and La d-states changes during CO2 chemoresistive sensing of La2O2CO3. The correlation between these spectroscopic findings with electrical resistance measurements leads to a more comprehensive understanding of the selective adsorption at La site and may enable the design of new materials for CO2 electrochemical applications.

scholarly journals Flow Cell for Operando X-Ray Photon-in-Photon-out Studies on Photo-Electrochemical Thin Film Devices

2020 ◽  
Author(s):  
Philipp Jäker ◽  
Dino Aegerter ◽  
Till Kyburz ◽  
Roman Staedler ◽  
Rea Fonjallaz ◽  
...  
Keyword(s):  
Thin Film ◽  
Water Oxidation ◽  
High Energy ◽  
Operating Conditions ◽  
High Energy Resolution ◽  
X Ray ◽  
Long Term Stability ◽  
Operando Xas ◽  
Artificial Photosynthetic ◽  
Thin Film Devices

Photo-electro-chemical (PEC) water splitting represents a promising technology towards an artificial photosynthetic device but many fundamental electronic processes, which govern long-term stability and energetics are not well understood. X-ray absorption spectroscopy (XAS), particularly its high energy resolution fluorescence-detected (HERFD) mode, emerges as a powerful tool to study photo-excited charge carrier behavior under operating conditions. The established thin film device architecture of PEC cells provides a well-defined measurement geometry, but it puts many constraints on conducting operando XAS experiments. So far, operando cells have not been developed that enable to concurrently measure highly intense X-ray fluorescence and photo-electro-chemical current without experimental artifacts caused by O<sub>2</sub> and H<sub>2</sub> bubbles formation. Moreover, we are missing a standardized thin film exchange procedure. Here, we address and overcome the instrumental limitations for operando HERFD-XAS to investigate photo- and electrochemical thin film devices. Our cell establishes a measurement routine that will provide experimental access to a broader scientific community, particularly due to the ease of sample exchange. Our operando photo-electro-chemical cell is optimized for the HERFD-XAS geometry and we demonstrate its operation by collecting high-resolution Fe K-edge spectra of hematite (α-Fe<sub>2</sub>O<sub>3</sub>) and ferrite thin film (MFe<sub>2</sub>O<sub>4</sub>, M= Zn, Ni) photoelectrodes during water oxidation.<br>

scholarly journals Introduction

1980 ◽  
Vol 5 ◽  
pp. 621-622
Author(s):  
H. van der Laan
Keyword(s):  
Good Deal ◽  
High Energy ◽  
General Assembly ◽  
High Energy Astrophysics ◽  
Optical Techniques ◽  
X Ray ◽  
Tremendous Progress ◽  
New Material ◽  
General Secretary

In the summer of 1977 the IAU General Secretary requested proposals for Joint Discussions at the XVIIth General Assembly more than two years later. As President of Commission 40 I wrote to other Commission Presidents proposing a J.D. on Extragalactic High Energy Astrophysics. The motivation was as follows, and I quote from my July 22, 1977 letter:“With the current advances in radio and optical techniques and the tremendous progress to be expected from the satellites HEAO-A and HEAO-B, to be launched respectively in the summer of 1977 and 1978, there should be a good deal of new material on high energy astrophysical phenomena in the extragalactic domain by the time of the 1979 General Assembly. Some of this will be of great cosmological significance and all of it will be astrophysically interesting. It is clear that the X-ray satellite results will get a lot of optical and radio follow-up and it therefore seems appropriate that a Joint Discussion of that topic be arranged at that time.”

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