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Segregation of NaBr in NaBr/NaCl crystals grown from aqueous solutions: Implications for sea salt surface chemistry
Author(s) -
Zangmeister Christopher D.,
Turner Jessica A.,
Pemberton Jeanne E.
Publication year - 2001
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2000gl012539
Subject(s) - x ray photoelectron spectroscopy , aqueous solution , analytical chemistry (journal) , scanning electron microscope , salt (chemistry) , chemistry , materials science , chemical engineering , chromatography , engineering , composite material
Surface segregation of NaBr in mixed NaBr/NaCl crystals precipitated from aqueous solutions containing Br is investigated. Crystals were grown from solutions of a wide range of Br:Cl values and studied using x‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy‐dispersive x‐ray fluorescence (EDX), and atomic force microscopy (AFM). Results indicate that NaBr surface‐segregates to cover 4–5% of the surface at the Br:Cl value found in sea water (1:660). The surface NaBr:NaCl values are ∼35 times higher those of the bulk crystals. The surface NaBr forms domains of average size 635 nm × 635 nm × 53 nm. Large areas of the surface contain NaCl with no detectable NaBr. Complete surface segregation of all Br found in sea salt particles is likely to occur, thereby making a greater amount of Br available for surface reactions with gas‐phase constituents than would be predicted based on bulk composition.