Possible modification of the structure of poly(acrylic) acid (PAA) membranes doped with graphite was investigated by UV-Vis and XRD techniques. The pure PAA membranes were characterized by good transparency in the domain 250-700 nm, with maximum absorption at 207 nm. The absorbance of membranes increased significantly after doping with graphite. The XRD patterns of pure membranes showed a low degree of order of the polymeric matrix.Some modifications of the parameters of the ordered domains of the polymer and of the graphite appeared at high concentrations of the dopant.
The magnetic and x-ray photoelectron spectroscopy (XPS) studies on the transition metal substituted, dimeric polyoxotungstate [Fe4(H2O)10(β-SbW9O33)2]6− are reported. The magnetic data were analyzed by using an isotropic Heisenberg Hamiltonian. The ground state of the frustrated molecule has a total spin of S=2. The XPS Fe 2p spectra suggest a 2+ formal valence state. The deviation from the contained Fe3+ ions can be explained by charge-transfer effects.
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