K-edge XANES analysis of sulfur compounds: an investigation of the relative intensities using internal calibration.
J Synchrotron Radiat
; 17(5): 683-8, 2010 Sep.
Article
em En
| MEDLINE
| ID: mdl-20724790
ABSTRACT
Sulfur K-edge XANES (X-ray absorption near-edge structure) spectroscopy is an excellent tool for determining the speciation of sulfur compounds in complex matrices. This paper presents a method to quantitatively determine the kinds of sulfur species in natural samples using internally calibrated reference spectra of model compounds. Owing to significant self-absorption of formed fluorescence radiation in the sample itself the fluorescence signal displays a non-linear correlation with the sulfur content over a wide concentration range. Self-absorption is also a problem at low total absorption of the sample when the sulfur compounds are present as particles. The post-edge intensity patterns of the sulfur K-edge XANES spectra vary with the type of sulfur compound, with reducing sulfur compounds often having a higher post-edge intensity than the oxidized forms. In dilute solutions (less than 0.3-0.5%) it is possible to use sulfur K-edge XANES reference data for quantitative analysis of the contribution from different species. The results show that it is essential to use an internal calibration system when performing quantitative XANES analysis. Preparation of unknown samples must take both the total absorption and possible presence of self-absorbing particles into consideration.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Compostos de Enxofre
/
Espectroscopia por Absorção de Raios X
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
J Synchrotron Radiat
Assunto da revista:
RADIOLOGIA
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Suécia