Criterious Preparation and Characterization of Earthworm-composts in View of Animal Waste Recycling: Part II. A Synergistic Utilization of EPR and ¹H NMR Spectroscopies on the Characterization of Humic Acids from Vermicomposts

Dehydrated halloysite intercalated mechanochemically with urea: Thermal behavior and structural aspects

“…The Fe (II) centers correspond to more symmetrical coordination sites in the halloysite structure and the Fe (I) centers to less symmetrical ones. All the spectra also present a broad absorption line in higher magnetic field, corresponding to overlapped lines of spin-spin coupling (bipolar interaction), proportional to r À3 , where r is the distance between two magnetic dipoles that interact with each other [27]. The broad line indicates the presence of magnetic dipole-dipole interactions among Fe 3+ ion centers and is referred to as a concentrated domain.…”

Use of Cu2+ as a metal ion probe for the EPR study of metal complexation sites in the double sulfite CuI 2SO3.CdII SO3 .2H2O

“…12 Observing the values of the EPR parameters for the other Cu II complexation site (Table 2), we note that they differ significantly from the more familiar copper complexes. For example, the value of the A 33 hyperfine coupling constant is appreciably lower than the value of A || generally found for a copper(II) ion.…”

Caracterização de adubos orgânicos por espectroscopia de ressonância paramagnética eletrônica

“…A adição desse solo à amostra 6 causou deformação na linha de base do sinal do RLO (Figura 3a) e aumento da ΔH PP (Figura 3b). Essas duas alterações são atribuídas ao surgimento de uma linha larga centrada em g ≈ 2,2 (dado não apresentado), gerada pela superposição de linhas decorrentes de interações dipolares entre estruturas ferromagnéticas (Guimarães et al, 2001). Contudo, não se exclui a possibilidade de alargamento espectral associado com o aumento da taxa de relaxação por interação dipolar (Novotny & Martin-Neto, 2002).…”