Generation of the radical cation of β-carotene in chloroform via the triplet state as revealed by time-resolved absorption spectroscopy

Upon anthracene-sensitized, triplet excitation of all-trans-β-carotene in n-hexane bleaching of Sn←S0 absorption and generation of Tn←T1 absorption were observed. In chloroform, in addition to the bleaching of the Sn←S0 absorption (0.676 ± 0.046 μs, with only little recovery of absorption) and generation of the Tn←T1 absorption (rise 0.670 ± 0.120 μs, decay 6.22 ± 0.11 μs), generation of the Dn←D0 absorption (rise 6.17 ± 0.56 μs, decay 0.489 ± 0.024 ms) was observed, indicating formation of the radical cation of β-carotene from the triplet state by electron transfer to chloroform.