Cations Strongly Reduce Electron Hopping-Times in Aqueous Solutions
2011 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 133, no 34, 13489-13495 p.Article in journal (Refereed) Published
We study how the ultrafast electron transfer between H2O molecules in liquid water upon absorption of soft X-ray radiation depends on the local molecular binding environment. Our probe is the resonant Auger-decay of the water O1s core-hole (~3.6 fs), by which we show that efficiency for electron delocalization can be significantly reduced when a first-shell water molecule is replaced by an atomic ion. Decays resulting from excitations at the O1s post-edge feature (~540 eV) of 6m LiBr and 3m MgBr2 aqueous solutions reveal electron hopping-times of approximately 1.5 and 1.9 fs, respectively – the latter represents a four-fold increase compared to the corresponding value in neat water. The slower electron delocalization in electrolytes, which shows a strong dependence on the charge of the cations, can be explained by ion-induced reduction of water-water orbital mixing. Density functional theory (DFT) electronic structure calculations of solvation geometries obtained from molecular dynamics simulations reveal that this phenomenon largely arises from electrostatic perturbations of ions on the solvating water molecules. Our results demonstrate that it is possible to deliberately manipulate charge-transfer rates in aqueous media.
Place, publisher, year, edition, pages
2011. Vol. 133, no 34, 13489-13495 p.
Atom and Molecular Physics and Optics Inorganic Chemistry
Research subject Physics; Chemistry with specialization in Inorganic Chemistry
IdentifiersURN: urn:nbn:se:uu:diva-151431DOI: 10.1021/ja204100jISI: 000295551600049OAI: oai:DiVA.org:uu-151431DiVA: diva2:409926