Characterization of Fe2+ Aqueous Solutions with Liquid Jet X-ray Photoelectron Spectroscopy: Chloride Depletion at the Liquid/Vapor Interface Due to Complexation with Fe2+

摘要

Liquid jet X-ray photoelectron spectroscopy is used under near ambient pressure conditions to characterize Fe2+ aqueous solutions. Counter ions, such as Cl- and Br- ions, added to the solution lead to changes in the first solvation sphere of the Fe-aqua complex in solution. Binding energy shifts of 0.4 eV to lower binding energy are observed in the Cl 2p spectra, 2 eV to higher binding energy in the Fe 2p spectra and no shifts are observed in the Br 3d spectra. Depletion of the Cl- species is observed at the interface, caused by coordination with Fe2+. Depletion of Cl- at the liquid/vapor interface may have significant impacts on oxidative chemistry at the interface of atmospheric aerosols that contain both chloride and iron. The Cl- complexation with the Fe2+ ions will also affect the Fenton chemistry that is dependent on this metal ion.