Computer Science
Scientific paper
Oct 1985
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1985gecoa..49.2081a&link_type=abstract
Geochimica et Cosmochimica Acta, vol. 49, Issue 10, pp.2081-2089
Computer Science
5
Scientific paper
X-ray absorption spectroscopy, including extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) techniques, have been used to determine the structure and speciation of complexes for Fe 2+ and Fe 3+ chloride solutions at a variety of pH's, ionic strengths, and chloride/iron ratios. Low intensity K-edge transition features and analysis of modified pair correlation functions, derived from Fourier transformation of EXAFS spectra, show a regular octahedral coordination of Fe(II) by water molecules with a first-shell Fe 2+ -O bond distance, closely matching octahedral Fe 2+ -O bonds obtained from solid oxide model compounds. Solution Fe 2+ -O bond distances decrease with chloride/iron ratio, pH, and total FeCl 2 concentration. A slight intensification of the 1 s 3 d transition with increasing FeCl 2 concentration suggests that chloride may begin to mix with water as a nearest-neighbor octahedral ligand. Fe 3+ solutions show a pronounced increase in the 1 s 3 d transition intensities between 1.0 M FeCl 3 /7.8 M Cl - to 1.0 M FeCl 3 / 15 M Cl - , indicating a coordination change from octahedral to tetrahedral complexes. EXAFS analyses of these solutions show an increase in first-shell Fe 3+ -ligand distances despite this apparent reduction in coordination number. This can be best explained by a change from regular octahedral complexes of ferric iron (either Fe(H 2 O) 6 3+ or trans-Fe(H 2 O) 4 Cl 2 or both; Fe 3+ -O bond distances of 2.10 Å) to tetra-chloro complexes [Fe 3+ -Cl bond distances of 2.25 Å].
Apted Michael J.
Brown Gerald E.
Waychunas Glenn A.
No associations
LandOfFree
Structure and specification of iron complexes in aqueous solutions determined by X-ray absorption spectroscopy does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Structure and specification of iron complexes in aqueous solutions determined by X-ray absorption spectroscopy, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Structure and specification of iron complexes in aqueous solutions determined by X-ray absorption spectroscopy will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1546147