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-beta-carotene in n-hexane bleaching of S-n <-- S-0 absorption and generation of T-n <-- T-1 absorption were observed. In chloroform, in addition to the bleaching of the S-n <-- S-0 absorption (0.676 +/- 0.046 mu s), with only little recovery of absorption and generation of the T-n <-- T-1 absorption (rise 0.670 +/- 0.120 mu s, decay 6.22 +/- 0.11 mu s), generation of the D-n <-- D-0 absorption (rise 6.17 +/- 0.56 mu s, decay 0.489 +/- 0.024 ms) was observed, indicating formation of the radical cation of p-carotene from the triplet state by electron transfer to chloroform. (C) 2000 Published by Elsevier Science B.V.