[Quenching of chlorophyll and pheophytin fluorescence with fucoxanthin]

Quenching of chlorophyll a and pheophytin a fluorescence with fucoxanthin in acetone and n-hexanole at room temperature was investigated. The relationship between fluorescence yield and concentration of the quencher is subject to Stern--Folmer relation. The velocity constants were calculated and the efficiency of fluorescence quenching was determined. The energetic estimation has shown that the fluorescence quenching mechanism when the excited chlorophyll a molecule collides with fucoxanthin molecule may involve electron transfer from chlorophyll to fucoxanthin. In case of pheophytin a transfer of the electron from fucoxanthin to pheophytin is likely to take place.