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"On the unusual fluorescence properties of xanthone in water
" B. Heinz, B. Schmidt, C. Root, H. Satzger, F. Milota, B. Fierz, T. Kiefhaber, W. Zinth and P. GilchPhys. Chem. Chem. Phys. 8 (2006) 3432-3439 Abstract: Photo-excited xanthone is known to undergo ultrafast intersystem crossing (ISC) in the 1 ps time domain. Correspondingly, its fluorescence quantum yield in most solvents is very small (10–4). Surprisingly, the quantum yield in water is 100 times larger, while ISC is still rapid (~ 1 ps), as seen by ultrafast pump probe absorption spectroscopy. Temperature dependent steady state and time resolved fluorescence experiments point to a delayed fluorescence mechanism, where the triplet 3nπ* state primarily accessed by ISC is nearly isoenergetic with the photo-excited 1ππ* state. The delayed fluorescence of xanthone in water decays with a time constant of 700 ps, apparently by internal conversion between the 3ππ* state and the lowest lying triplet state 3ππ*. BMO authors (in alphabetic order): Peter Gilch Bjoern Heinz Christopher Root Helmut Satzger Bernhard Schmidt Wolfgang Zinth Assoziierte Projekte: Peptide and protein folding Ultrafast Intersystem Crossing in Aromatic Carbonyl Compounds  WWW-Version |