Laser-Induced Luminescence of Flavinium Salts

✍ Scribed by Antonie J. W. G. Visser; Arie Van Hoek; Franz Müller

• Publisher: John Wiley and Sons
• Year: 1980
• Tongue: German
• Weight: 450 KB
• Volume: 63
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19800630521

✦ Synopsis

Abstract

Flavinium salts dissolved in an ethanolic glass exhibit blue fluorescence and orange‐red phosphorescence upon excitation with a UV. line from an argon ion laser equipped with UV. optics. This arrangement enables the wavelength distribution and the time‐dependence of the phosphorescence to be measured in a relatively short time. Four cationic flavins were investigated. In spite of the small difference in the chemical structure of the compounds studied, large differences in the spectral shapes and in the ratio of quantum efficiencies of phosphorescence and fluorescence became apparent. The phosphorescence lifetimes were of the same order of magnitude, which indicated a similar rate of depletion of the lowest excited triplet state for all four cations. However, the efficiency of triplet formation (intersystem crossing) is affected by slight structural modifications in the pyrimidine subnucleus of the flavinium salt. The results point to a possible role of vibronic spin‐orbit coupling in the intersystem crossing.