Data/hora: 17/06/2024 03:25:23

Biblioteca(s): 	Embrapa Instrumentação.	
Data corrente: 	28/04/2003	
Data da última atualização: 	28/04/2003	
Autoria: 	NOVOTNY, E. H.; MARTIN-NETO, L.	
Afiliação: 	Embrapa Instrumentação Agropecuária, São Carlos, SP.	
Título: 	Effects of humidity and metal ions on the free radicals analysis of peat humus.	
Ano de publicação: 	2002	
Fonte/Imprenta: 	Geoderma, Amsterdam, v. 106, p. 305-317, 2002.	
Idioma: 	Inglês	
Conteúdo: 	The effects of humidity and metal ions in the determination of humic organic free radicals concentration (HOFRC) were studied by electron paramagnetic resonance (EPR). Increasing the sample humidity caused a decrease in both HOFRC, probably due to free radicals recombination, and in the derivative peak-to-peak line width, probably due to a higher spin-spin relaxation  time (T2) as the molecular mobility increasd (shorter correlation time). Diamagnetic ions did not affect the HOFRC, while paramagnetic ions induced an intense HOFRC decrease. This effect was associated with dipolar-relaxation enhancement at high (above 0, 01%) paramagnetic ion concentrations, since the inhomogeneity parameter decreased to less than I. Further, a possible exchange interaction an/or shift in the free radicals equilibrium reactions might have occurred at low paramagnetic ion concentrations (below 0,01%.	
Palavras-Chave: 	Radicais livres; Ressonânica paramagnética; Substâncias húmicas.	
Thesaurus Nal: 	free radicals; ions.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Instrumentação (CNPDIA)	
Exemplares: 	CNPDIA - (7463-1) - UPC - SP - -- - PROCI-02.00014 -  - 02.0000014 - DIS