Structural environment of krypton dissolved in vitreous silica

X-ray absorption measurements on Kr dissolved homogeneously in vitreous silica (1.97 wt% Kr) have been carried out at the Kr K-edge at 4.5 K, representing the first direct determination of the sites occupied by a noble gas. The presence of EXAFS oscillations shows that the Kr atoms are surrounded by...

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Bibliographic Details
Published in:The American mineralogist 1999-09, Vol.84 (9), p.1461-1463
Main Authors: Wulf, Reinhard, Calas, George, Ramos, Aline, Büttner, Heinz, Roselieb, Knut, Rosenhauer, Matthias
Format: Article
Language:English
Subjects:
absorption
Gases
Geochemistry
Krypton
Mineralogy
Minerals
noble gases
Silica
volatiles
X-ray data
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Summary:X-ray absorption measurements on Kr dissolved homogeneously in vitreous silica (1.97 wt% Kr) have been carried out at the Kr K-edge at 4.5 K, representing the first direct determination of the sites occupied by a noble gas. The presence of EXAFS oscillations shows that the Kr atoms are surrounded by a well-defined shell of nearest neighbors, identified as oxygen atoms. The mean Kr-O distances are 3.45±0.1 Å, based on a simple model of Gaussian disorder, with a Debye-Waller factor of σ2 = 0.06 Å2. The large Kr-O distance, which is at the upper limit of the size of the holes existing in vitreous silica, together with the existence of well-defined sites suggests a forced, densely packed environment of oxygen around Kr atoms characteristic of clathrasil surroundings.
ISSN:0003-004X
1945-3027
DOI:10.2138/am-1999-0927