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Metal K-edge

The hexafluorides [RuFg] and [OsFg] are known. The rather unstable RuFg can be obtained as a brown solid in high yield by the interaction of [RuFs] with F2 at 220 °C and 30 atm. The IR spectrum is consistent with an octahedral geometry. " The metal K-edge EXAFS data for RuFg have been obtained and a Ru F distance of 1.83 A was found. ... [Pg.799]

A representative XAS spectrum (metal K-edge) is generally divided into four regions, as indicated in Figure 1.18. [Pg.23]

Metal L-edge XAS mostly focuses on transitions from the 2p6 core. The 2p —> 3d and 2p —> 4s are electric dipole allowed with the p - - d channel being 20-fold more intense.52 Therefore, L-edges are a more direct method to study d valence levels relative to the metal K-edges. Also, the spectra are taken at much lower photon... [Pg.28]

Fig. 1 Energy level diagram comparing d — d transitions, metal L-edge and metal K-edge excitations for first transition series elements... Fig. 1 Energy level diagram comparing d — d transitions, metal L-edge and metal K-edge excitations for first transition series elements...
Fig. 2 The basic features of a metal K-edge X-ray absorption spectrum highlighted on the spectra of two classical coordination compounds D4h CuCl42 (pale line) and CuCl42- (dark line). The inset shows the pre-edge region is expanded at the bottom [22]... Fig. 2 The basic features of a metal K-edge X-ray absorption spectrum highlighted on the spectra of two classical coordination compounds D4h CuCl42 (pale line) and CuCl42- (dark line). The inset shows the pre-edge region is expanded at the bottom [22]...
As for the metal K-edges above, it is important to first consider the simple 3d9 Cu(II) electron configuration. In this case, the L-edge involves a Cu 2p —> 3d transition which is electric dipole allowed and produces a 2p53d10 final state. [Pg.169]

Metal L edge 3- to 4-fold higher resolution than metal K edge allowed 2p-3d transitions are observed metal L edge contains information on spin state, oxidation state, and LF splitting of d orbitals intensity probes metal-ligand covalency L edge MCD possesses similar information content to MCD described above... [Pg.74]

Figure 2 Molybdenum K-edge X-ray absorption spectrum, ln(i /i ) versus X-ray energy (eV), for molybdenum metal foil (25- jjn thick), obtained by transmission at 77 K with synchrotron radiation. The energy-dependent constructive and destructive interference of outgoing and backscattered photoelectrons at molybdenum produces the EXAFS peaks and valleys, respectively. The preedge and edge structures marked here are known together as X-ray absorption near edge structure, XANES and EXAFS are provided in a new compilation of literature entitled X-rsy Absorption Fine Structure (S.S. Hasain, ed.) Ellis Norwood, New York, 1991. Figure 2 Molybdenum K-edge X-ray absorption spectrum, ln(i /i ) versus X-ray energy (eV), for molybdenum metal foil (25- jjn thick), obtained by transmission at 77 K with synchrotron radiation. The energy-dependent constructive and destructive interference of outgoing and backscattered photoelectrons at molybdenum produces the EXAFS peaks and valleys, respectively. The preedge and edge structures marked here are known together as X-ray absorption near edge structure, XANES and EXAFS are provided in a new compilation of literature entitled X-rsy Absorption Fine Structure (S.S. Hasain, ed.) Ellis Norwood, New York, 1991.
Figures Background-subtracted, normalized, and ili -weighted Mo K-edge EXAFS, versus k (A ), for molybdenum metal foil obtained from the primary experimental data of Figure 2 with Eq = 20,025 eV. Figures Background-subtracted, normalized, and ili -weighted Mo K-edge EXAFS, versus k (A ), for molybdenum metal foil obtained from the primary experimental data of Figure 2 with Eq = 20,025 eV.
Figures Fourier transform (soiid curve), Osir ) versus r (A, without phase-shift correction), of the Mo K-edge EXAFS of Figure 5 for moiybdenum metal foii. The Fourier filtering window (dashed curve) is applied over the region -1.5-4.0 A to isolate the two nearest Mo-Mo peaks. Figures Fourier transform (soiid curve), Osir ) versus r (A, without phase-shift correction), of the Mo K-edge EXAFS of Figure 5 for moiybdenum metal foii. The Fourier filtering window (dashed curve) is applied over the region -1.5-4.0 A to isolate the two nearest Mo-Mo peaks.
It is known that thin (-20 A) passive films form on iron, nickel, chromium, and other metals. In s ressive environments, these films provide excellent corrosion protection to the underlying metal. The structure and composition of passive films on iron have been investigated through iron K-edge EXAFS obtained under a variety of conditions, yet there is still some controversy about the exact nature of... [Pg.224]

The copper EXAFS of the ruthenium-copper clusters might be expected to differ substantially from the copper EXAFS of a copper on silica catalyst, since the copper atoms have very different environments. This expectation is indeed borne out by experiment, as shown in Figure 2 by the plots of the function K x(K) vs. K at 100 K for the extended fine structure beyond the copper K edge for the ruthenium-copper catalyst and a copper on silica reference catalyst ( ). The difference is also evident from the Fourier transforms and first coordination shell inverse transforms in the middle and right-hand sections of Figure 2. The inverse transforms were taken over the range of distances 1.7 to 3.1A to isolate the contribution to EXAFS arising from the first coordination shell of metal atoms about a copper absorber atom. This shell consists of copper atoms alone in the copper catalyst and of both copper and ruthenium atoms in the ruthenium-copper catalyst. [Pg.257]

FIGURE 27.13 Cu K edge XANES spectra for a Cu full layer in sulfate solution at 0.2 V (SCE) in parallel (solid line) and perpendicular (dotted line) polarizations and for metallic copper (dashed line). (Erom Soldo et al., 2002, with permission from Elsevier.)... [Pg.482]

Experimental evidence of the —S03" H0Si— interaction have been obtained from IR, Rh K-edge EXAFS, and CP MAS 3 IP NMR studies. These supported catalysts have been tested for the hydrogenation and hydroformylation of alkenes. No Rh leaching was observed.128-130 An extension to the immobilization of chiral metal complexes for asymmetric hydrogenation is reported below. [Pg.456]


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See also in sourсe #XX -- [ Pg.24 , Pg.25 , Pg.26 , Pg.27 ]




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K edges

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