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In X-ray absorption spectroscopy, the K-edge is a sudden increase in x-ray absorption occurring when the energy of the X-rays is just above the binding energy of the innermost electron shell of the atoms interacting with the photons. The term is based on X-ray notation, where the innermost electron shell is known as the K-shell. Physically, this sudden increase in attenuation is caused by the photoelectric.
5/26/1998 · The sulfur K-edge spectra for whole human blood, plasma, and erythrocytes are shown. The erythrocyte sulfur K-edge spectrum is similar to that of fully reduced glutathione. Simulation of the plasma spectrum indicated 32% thiol and 68% disulfide sulfur. The whole blood spectrum can be simulated by a combination of 46% disulfide and 54% thiol sulfur.
S K-edge X-ray absorption spectroscopy (XAS) is a direct experimental probe of metal ion electronic structure as the pre-edge energy reflects its oxidation state, and the energy splitting pattern of the pre-edge transitions reflects its spin state.
Metal K- vs S K-Edge 1. Pre-edge feature is dipole-forbidden : 111s to 3d transition 1. Pre-edge feature is dipole-allowed : 1s 11to 3p&4p transition The result is an inherently sharper, feature-rich S K-edge spectrum 2. At higher energy the peaks are 11broader. e.g at 9000 eV (Cu), the 11natural width is 1.55 eV 2. At S K-edge energies the peaks are, 6/10/2009 · S K-edge XAS has previously been used to investigate the effect of H-bonding in the active sites of Fe-S electron transfer proteins. 14 XAS data on the proteins showed significant reductions of M-S bond covalency relative to model complexes which qualitatively correlated to the H-bonding interactions in the active site. 16 – 18 For a quantitative estimate of this effect, S K-edge XAS was performed on a.
Sulfur K-edge X-ray absorption spectroscopy (XAS) has been used to distinguish between aqueous and solid sulfates and to investigate changes in their speciation. Data have been collected for tetrahedrally coordinated S in K 2 SO 4 and KHSO 4 solids and aqueous solutions. With a first qualitative analysis of the X-ray absorption near-edge structure (XANES) spectra, it has been observed that those for solids.
S K -edge XAS and DFT Calculations on Cytochrome P450: Covalent and Ionic Contributions to the Cysteine-Fe Bond and Their Contribution to Reactivity. Abhishek Dey †, Yonging Jiang §, Paul Ortiz de Montellano * §, Keith O. Hodgson * † ‡, Britt Hedman * ‡, and ; Edward I. Solomon * † ‡
