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Raman microspectrometric study of the dissolution layer of M(NO 3 ) 2 · n H 2 O crystals (M = Mg, Ca, Zn and Cd) in their undersaturated aqueous solutions
Author(s) -
Koussinsa Félix,
Bertin François
Publication year - 1991
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250220306
Subject(s) - dissolution , raman spectroscopy , chemistry , ion , analytical chemistry (journal) , metal , divalent , crystallography , crystal (programming language) , composition (language) , inorganic chemistry , chromatography , optics , physics , organic chemistry , linguistics , philosophy , computer science , programming language
The composition of the dissolution layer of certain divalent metal nitrates crystals such as Mg(NO 3 ) 2 , Ca(NO 3 ) 2 , Zn(NO 3 ) 2 and Cd(NO 3 ) 2 in their respective undersaturated solutions was studied by Raman microspectrometry using multi‐channel acquisition of data. A preliminary examination of homogeneous saturated and 20% undersaturated solutions of every solute considered confirmed the existence of individual Raman bands which could be assigned to different solvated species, namely free aquated ions, solvent‐separated ion pairs and contact ion pairs. Some spectral differences were noted between the four cations involved. With Ca 2+ , Zn 2+ and Cd 2+ a weak band, assigned to ion aggregates, was also identified. Micro‐Raman spectra of dissolution layers recorded at several steps of the crystal dissolution showed a considerable increase in the proportions of aggregates or contact ion pairs, depending on the type of solute examined. Sharp differences between the dissolution layer composition for Group IA, IIA and IIB metal nitrates were observed.