"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. Gilch
Phys. Chem. Chem. Phys. 8 (2006) 3432-3439
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):
Peptide and protein folding
Ultrafast Intersystem Crossing in Aromatic Carbonyl Compounds