Femtosecond photodynamics of the reverse (P-15E(fr) -> P-15Z(r))reaction of the red/far-red phytochrome Cph1 from Synechocystis were resolved with visible broadband transient absorption spectroscopy. Multi-phasic dynamics were resolved and separated via global target analysis into a fast-decaying (260 fs) excited-state population that bifurcates to generate the isomerized Lumi-F primary photoproduct and a nonisomerizing vibrationally excited ground state that relaxes back into the P-15E(fr) ground state on a 2.8-ps time scale. Relaxation on a 1-ms timescale results in the loss of red absorbing region, but not blue region, of Lumi-F, which indicates that formation of P-15Z(r) occurs on slower timescales. (c) 2012 Elsevier B.V. All rights reserved.