Determination of the S2 lifetime of β-carotene

Abstract The S2 lifetime of β-carotene has been determined by both femtosecond transient absorption experiments and emission yield studies. For β-carotene dissolved in ethanol and in CS2, the initially excited S2 was found to live for 200 to 250 fs at room temperature. Implications of this result for carotenoid-to-chlorophyll energy transfer in photosynthetic systems are discussed.