Elements of group 5

Sowerby, D. Bryan

doi:10.1016/s0010-8545(00)82040-8

Cited by 4 publications

(1 citation statement)

References 386 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The EXAFS spectra of the solid thioarsenates show an As V −S backscattering peak at R ≈ 1.8 Å (uncorrected for phase shift) besides the As V −O backscattering peak at R ≈ 1.3 Å, which is the characteristic shell in As 2 O 5 (Figure ). Even though all thioarsenate synthesis products are sodium salts, detection of Na backscattering atoms by EXAFS is not expected due to the large distance and substantial disorder in the solid salts. ,,,− The peak at R ≈ 1.3 corresponds to a fitted As−O bond length of 1.70 Å for mono- and dithioarsenate. This bond length matches the crystal structure data for (thio)arsenates (As−O bond length 1.67−1.69 Å; cf.…”

Section: Resultssupporting

confidence: 65%

Discrimination of Thioarsenites and Thioarsenates by X-ray Absorption Spectroscopy

et al. 2009

View full text Add to dashboard Cite

Soluble arsenic-sulfur compounds play important roles in the biogeochemistry of arsenic in sulfidic waters but conflicting analytical evidence identifies them as either thioarsenates (= As(V)-sulfur species) or thioarsenites (= As(III)-sulfur species). Here, we present the first characterization of thioarsenates (mono-, di-, and tetrathioarsenate) by X-ray absorption spectroscopy and demonstrate that their spectra are distinctly different from those of As(III)-sulfur species, as well as from arsenite and arsenate. The absorption near edge energy decreases in the order arsenate > thioarsenates > arsenite > As(III)-sulfur species, and individual thioarsenates differ by 1 eV per sulfur atom. Fitted As(V)-S and As(V)-O bond distances in thioarsenates (2.13-2.18 A and 1.70 A, respectively) are significantly shorter than the corresponding As(III)-S and As(III)-O bond distances in As(III)-S species (2.24-2.34 A and 1.78 A, respectively). Finally, we demonstrate that thioarsenates can be identified by principal component analysis in mixtures containing As(III)-sulfur species. This capability is used to study the spontaneous reduction of tetrathioarsenate to As(III)-sulfur species (possibly trithioarsenite) upon acidification from pH 9.5 to 2.8.

show abstract