Mechanisms of deactivation processes of excited uranyl ion

Zsolt Fazekas, Hlroshi Tomiyasu, Yoon Yul Park, Tomoo Yamamura, Masayuki Harada

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

The paper summarizes some results on the photochemistry of uranyl (UO22+) ion. The dual luminescence of uranyl ion in aqueous solutions was explained by a rather simple mechanism, i.e., emissions from two different excited species, excited aquo and hydrolyzed ions, *UO22+ and *[(UO2)2(OH)2]2+, respectively. This mechanism was based on the slow ligand exchange rate of [(UO2)2(OH)2]2+ compared with the deactivation time scale. The deactivation mechanism by water molecules in the absence of quenchers was also studied. The possibility of energy transfer and deuterium isotope effect on the uranyl lifetimes is discussed. 17O-NMR spectra of uranyl samples simultaneously irradiated by laser was measured. It was found that the chemical shift and the line width of 16O-U-17O signal were influenced by the laser intensity, which was interpreted by paramagnetic interactions with excited uranyl ion. Detailed analysis of nanosecond flash photolysis experiments indicated die energy transfer f.-4m *UO22+ to dysprosium ion. In solutions containing UO22+ and Dy3+, the 414 nm laser irradiation resulted the excitation of Dy3+ despite no absorption due to Dy3+ in this wavelength. The time resolved spectra of sensitized emission of *Dy3+ was also observed.

Original languageEnglish
Pages (from-to)783-797
Number of pages15
JournalACH - Models in Chemistry
Volume135
Issue number5
Publication statusPublished - 1998 Dec 1

ASJC Scopus subject areas

  • Chemistry(all)

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