搜索结果: 1-15 共查到“理学 X-ray absorption”相关记录20条 . 查询时间(0.125 秒)
X-ray absorption by the low-redshift intergalactic medium: A numerical study of the Lambda cold dark matter model
theory intergalactic medium
2014/12/24
Using a hydrodynamic simulation of a cold dark matter universe with a cosmological constant, we investigate the "X-ray forest" absorption imprinted on the spectra of background quasars by the interven...
X-Ray Absorption Line Spectroscopy of the Galactic Hot Interstellar Medium
Cyg X–2 V801 Ara
2014/12/24
We present an X-ray absorption line spectroscopic study of the large-scale hot interstellar medium (HISM) in the Galaxy. We detect Ne IX Kα absorption lines in the Chandra grating spectra of seven Gal...
X-Ray Absorption Spectroscopy of the Multiphase Interstellar Medium: Oxygen and Neon Abundances
ISM 4U 1820–303
2014/12/24
X-ray absorption spectroscopy provides a powerful tool in determining the metal abundances in various phases of the interstellar medium (ISM). We present a case study of the sight line toward 4U 1820-...
Although the existence of large-scale hot gaseous halos around massive disk galaxies has been theorized for a long time, there is yet very little observational evidence. We report the Chandra and XMM-...
Redox states of thirteen shergottites as inferred from iron micro X-ray absorption near edge structure of maskelynite
shergottite X-ray Absorption Near Edge Structure Mars maskelynite redox stat
2017/4/10
We used synchrotron radiation Fe micro-XANES (X-ray Absorption Near Edge Structure) analysis to determine the
iron valence of maskelynite (shocked-plagioclase glass) in thirteen shergottites, and we ...
Role of quantum nuclei and local fields in the x-ray absorption spectra of water and ice
Role of quantum nuclei local fields the x-ray absorption spectra of water and ice Chemical Physics
2012/4/19
We calculate the x-ray absorption spectra of liquid water at ambient conditions and of hexagonal ice close to melting, using a static GW approach that includes approximately local field effects. Quant...
The effects of X-ray absorption variability in NGC 4395
galaxies: active – galaxies: individual: NGC 4395 – X-rays: galaxies
2011/10/8
We present a new X-ray analysis of the dwarf Seyfert galaxy NGC 4395, based on two archival XMM-Newton and Suzaku observations. This source is well known for a series of remarkable properties: one of ...
Local electronic structure of Fe$^{2+}$ impurities in MgO thin films: Temperature-dependent soft x-ray absorption spectroscopy study
Local electronic structure of Fe$^{2+}$ impurities Temperature-dependent soft x-ray absorption spectroscopy study
2010/11/18
We report on the local electronic structure of Fe impurities in MgO thin films. Using soft x-ray absorption spectroscopy (XAS) we verified that the Fe impurities are all in the 2+ valence state.The fi...
The importance of inter-site coherences in the x-ray absorption spectra of mixed-valent systems
inter-site coherences in the x-ray mixed-valent systems
2010/11/19
We study the importance of inter-site coherences and quantum interference effects in
the x-ray absorption spectroscopy (XAS) of mixed-valent systems. We demonstrate its importance,
first for a simpl...
Quantitative Estimation Methods for Concentrations and Layer Thicknesses of Elements Using Edge-jump Ratios of X-ray Absorption Spectra
Quantitative Estimation Methods Concentrations Layer Thicknesses Elements Using Edge-jump Ratios of X-ray Absorption Spectra
2010/9/17
This work concerns the development of quantitative estimation techniques using the K edge-jump ratio of X-ray absorption spectrum recorded through total-electron-yield measurements. The three methods ...
Determination of the host phase of rare earth elements in natural carbonate using X-ray absorption near-edge structure
rare earth elements yttrium XANES carbonate
2017/8/9
The Y K-edge X-ray absorption near-edge structure (XANES) spectra of various materials were measured to investigate whether rare earth elements (REEs) are incorporated in carbonate phase or in other m...
Direct measurement of the soil water retention curve using X-ray absorption
X-ray absorption soil hydraulic properties soil water dynamics Richards’equation
2009/3/3
X-ray absorption measurements have been explored as a fast experimental approach to determine soil hydraulic properties and to study rapid dynamic processes. As examples, the pressure-saturation relat...
Structural Chemistry of Fe, Mn, and Ni in Synthetic Hematites as Determined by Extended X-Ray Absorption Fine Structure Spectroscopy
EXAFS Fe Oxides Hematite Metal Substitution Trace Elements XAS XRD
2011/12/6
Abstract: The incorporation of transition metals into hematite may limit the aqueous concentration and bioavailabity of several important nutrients and toxic heavy metals. Before predicting how hemati...
Reduction and Sorption of Chromium by Fe(II)-Bearing Phyllosilicates: Chemical Treatments and X-Ray Absorption Spectroscopy (XAS) Studies
Absorption Chromium EXAFS Phyllosilicates Reduction XANES
2011/12/6
Abstract: The reduction of hexavalent chromium species in aqueous solutions by interaction with Fe(II)-bearing solid surfaces was studied using a 0.96 × l0−3 M Cr(VI) solution and iron-rich clay...
Ultrafast extended x-ray absorption fine structure„EXAFS…—theoretical considerations
extended x-ray absorption fine structure EXAFS… —theoretical considerations
2014/9/24
Inspired by the recent experimental demonstration of ultrafast x-ray absorption spectroscopy, we present a framework for the calculation of extended x-ray absorption fine structure~EXAFS!spectra on th...