The transient absorption recovery induced in phycocyanin trimers by picosecond pulses of
variable wavelength (570 — 620 nm) has been recorded and analyzed by applying a least-squares
multi-exponential fit procedure.
The results suggest that in native PC trimers the chromophores exhibit a microheterogeneity
with the effect that the derived apparent lifetimes are functions of excitation and probing wavelength.
It is suggested that, due to strong excitonic coupling between a-84 and ß-84
chromophores, the lifetime of the terminal acceptor state is reduced to about 900 ps; the apparent
energy transfer time from chromophore β-155 to a-84 and ß-84 chromophores varies between
20—50 ps depending on the actual chromophore-protein arrangement (microheterogeneity)
