Fluorescence of europium(III) trapped in silica gel-glass as a probe for cation binding and for changes in cage symmetry during gel dehydration
✍ Scribed by D. Levy; R. Reisfeld; D. Avnir
- Publisher
- Elsevier Science
- Year
- 1984
- Tongue
- English
- Weight
- 464 KB
- Volume
- 109
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
Tke fiuorescerwe of EnBfZ) is a sensitive probe for the gel-glass trarxifoxmation. SiEca gel-ghss containing Eu@Q was prepared by hydrolysis of tetramethosysilane. The tot& fluorescence of Eu@I) from the sflo electronic state ex-Mbits a gradual increase and a relative increase of intensity of the hypersensitive trmsition sE>o -t 'Fz as a function of time and temperature of dehydration of the gel. This behavior is explained by formation of a chemical bond between Eu(IIi) and the oxygens of the silicate group whereby Eu(II1) acquires a symmetry similar to that in a regular glass obtained by melting the appropriate oxides. The degeneracy of the 'Fr and 7F~ states is removed in low-symmetry sites in the glass as reflected by the hatf-\rvidth of the emission bands.