Fig. 3.

The chemical, kinetic mechanisms. (A) General chemical, kinetic mechanism that generates three relaxation times. The state IS1 is the first observed intermediate after the illumination of the dark state pG. The activated molecules relax through two ISs, IS2, and IS3, to the dark state pG. The direct path from IS1 to the dark state pG is not considered. (B–E) Subsets of the general scheme compiled by setting certain rate coefficients to 0. (B) S, Irreversible, sequential mechanism. (C) P, Parallel mechanism. (D) DE, Mechanism with a dead end. (E) SP, Semiparallel mechanism.