Dual Fluorescence of Novel Modified Carotenoids

Abstract

Despite only a small energy difference between the lowest energy excited singlet states S1 and S2, both the carotenoids 1 and 2 exhibit dual fluorescence. For the first time the energetic position of the S1 state, which is not accessible by UV/VIS excitation, could be estimated. In 1 it lies 3000–3500 cm−l lower than the S2 state; in 2 this gap is 3400–4000 cm−1, which is also presumed to be the S2–S1 difference in β-carotene.