Transient Absorption Study of Peridinin and Peridinin−Chlorophyll a−Protein after Two-Photon Excitation

This is the authors' abstract. We don't add key points for this paper.

Two-photon excited pump−probe spectroscopy was carried out on the peridinin−chlorophyll a −protein complex (PCP) and on the peridinin molecule in methanol solution. Our data are consistent with earlier two-photon fluorescence excitation spectra 1,2 and lead to the conclusion that, for peridinin in methanol solution, a separate two-photon-allowed transition exists just to the red of the strongly allowed S 0 − S 2 (B u + ) band. In the PCP complex, two-photon excitation at 1150 nm can also be interpreted as preparing a new state. In both cases, the new state is most likely the S 1 (A g - ) state. It is not yet possible to conclude experimentally whether peridinin possesses a single low lying state with solvent dependent properties or two distinct states, the A g - and the charge transfer states.