M. Alves Marques
University of Lisbon
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Featured researches published by M. Alves Marques.
Journal of Physics: Condensed Matter | 2001
M. Alves Marques; M.I Cabaço; M.I. de Barros Marques; A.M. Gaspar; C M de Morais
Concentrated aqueous solutions of lanthanum chloride (3.4 molal) and bromide (3.2 molal) were investigated by x-ray diffraction, EXAFS and Raman spectroscopy. The observation of narrow maxima of intensity in the diffraction patterns is well interpreted as arising from positional correlations between the hydrated cations present in these solutions. Raman spectra, exhibiting a single polarized band (~350 cm-1), suggest that only one kind of aggregate is observed in these solutions. EXAFS results allowed us to establish the distances of (plausibly) nine water molecules around each lanthanum cation. The persistence of lanthanum hydrates has been followed from very concentrated solutions (~3 molal) up to diluted ones (~0.5 molal) by x-ray diffraction as well as by EXAFS. Previous investigations are discussed, too.
Journal of Physics: Condensed Matter | 1992
M.I. de Barros Marques; M. Alves Marques; J. Resina Rodrigues
Yttrium hydrates with eight-coordinated water molecules seem to be the predominant species in concentrated aqueous solutions of yttrium bromide and chloride. For molarities from approximately 2.1 down to 0.6M in H2O EXAFS experiments yield an average Y3+-O distance of 2.33+or-0.02 AA for the YBr3 and 2.34+or-0.02 AA for the YCl3. Investigations by means of Raman spectroscopy with substitution of the solvent by D2O for a 2.1M solution of YCl3 lead to an isotopic shift of 1.052+or-0.007 for the polarized band assigned to the stretching vibrational mode of the complex, which corroborates the idea of the presence of a (relatively) stable hydrate of the yttrium ion.
Journal of Molecular Liquids | 2005
M. Isabel Cabaço; M.I. de Barros Marques; M. Alves Marques; A.M. Gaspar; M.L. de Almeida
Journal of Molecular Liquids | 2004
M. Alves Marques; M.I. de Barros Marques; M. Isabel Cabaço; A.M. Gaspar; M.L. de Almeida
Journal of Molecular Liquids | 2003
A.M. Gaspar; M. Alves Marques; M.I Cabaço; M.I. de Barros Marques; T Buslaps; V Honkimaki
Journal of Molecular Liquids | 2007
M. Alves Marques; M.I. de Barros Marques; M. Isabel Cabaço; A.M. Gaspar; M. P. M. Marques; Ana M. Amado; A. M. Amorim da Costa
Journal of Molecular Liquids | 2007
M. Isabel Cabaço; M.I. de Barros Marques; A.M. Gaspar; M. Alves Marques; M. Margarida Costa
Journal of Physics: Condensed Matter | 2010
A.M. Gaspar; M. Alves Marques; Maria Isabel Cabaco; M.I. de Barros Marques; Alexander I. Kolesnikov; John Tomkinson; Jindong Li
Acta Crystallographica Section A | 1984
M.I. Cabaço; M. Alves Marques
Acta Crystallographica Section A | 1984
J.M.S. de Almeida Casimiro; M.I. de Barros Marques; M. Alves Marques