Fig. (5).

Schematic representation of electron spin polarization transfer in zero-field between the Chl a donor and the Per acceptor occurring during TTET. The size of the circles expresses the intersystem crossing population probabilities of the triplet sublevels for Chl a. The orientation of the ZFS tensor axes for Chl a and Per is reported. As an example, an hypothetical relative orientation of the ZFS is also represented, where the X,Y and Z axes of TChl a are respectively parallel to Z, X and Y axes of the ^TPer.