This study investigates biogeochemical reductive release of arsenate from beudantite into solution in a crater area in northern Taiwan,using a combination of X-ray absorption near-edge structure （XANES） and atomic a...This study investigates biogeochemical reductive release of arsenate from beudantite into solution in a crater area in northern Taiwan,using a combination of X-ray absorption near-edge structure （XANES） and atomic absorption spectrometry.Total arsenic （As） concentrations in the soil were more than 200 mg/kg.Over four months of laboratory experiments,less than 0.8% As was released into solution after reduction experiments.The 71% to 83% As was chemically reduced into arsenite （As（III）） and partially weathering into the soluble phase.The kinetic dissolution and re-precipitation of As,Fe,Pb and sulfate in this area of paddy soils merits further study.展开更多
Mass-selected anionic cobalt clusters of two different sizes （Co2 and Co13） were deposited onto ultrathin NaC1 films grown on an Au（111） substrate. Using scanning tunneling microscopy experiments and density funct...Mass-selected anionic cobalt clusters of two different sizes （Co2 and Co13） were deposited onto ultrathin NaC1 films grown on an Au（111） substrate. Using scanning tunneling microscopy experiments and density functional theory simulations, we show that the deposited Co2 cluster dissociates and that the resulting Co atoms dope the NaCI surface by substituting Na ions. In contrast, the larger Co13 cluster does not dissociate and remains stable on top of the NaC1 film. The size- dependent fragmentation of clusters is an important aspect in the understanding of the chemical interaction between size-selected small aggregates of atoms and supporting surfaces.展开更多
基金supported by the "National" Science Council,Taiwan(No.NSC100-2313-B002-007)
文摘This study investigates biogeochemical reductive release of arsenate from beudantite into solution in a crater area in northern Taiwan,using a combination of X-ray absorption near-edge structure （XANES） and atomic absorption spectrometry.Total arsenic （As） concentrations in the soil were more than 200 mg/kg.Over four months of laboratory experiments,less than 0.8% As was released into solution after reduction experiments.The 71% to 83% As was chemically reduced into arsenite （As（III）） and partially weathering into the soluble phase.The kinetic dissolution and re-precipitation of As,Fe,Pb and sulfate in this area of paddy soils merits further study.
文摘Mass-selected anionic cobalt clusters of two different sizes （Co2 and Co13） were deposited onto ultrathin NaC1 films grown on an Au（111） substrate. Using scanning tunneling microscopy experiments and density functional theory simulations, we show that the deposited Co2 cluster dissociates and that the resulting Co atoms dope the NaCI surface by substituting Na ions. In contrast, the larger Co13 cluster does not dissociate and remains stable on top of the NaC1 film. The size- dependent fragmentation of clusters is an important aspect in the understanding of the chemical interaction between size-selected small aggregates of atoms and supporting surfaces.
