Figure 4.

A and B, Kinetics of difference absorption induced by saturating laser excitation in whole cells of strains Fud7-P71 (A) and FN68 (B) at room temperature in the 0.5- to 100-μs time range. Detection wavelengths were as follows: 540 nm (squares), 545 nm (circles), 550 nm (triangles), 555 nm (stars), 560 nm (diamonds), and 565 nm (hexagons). Continuous lines are the fit to the experimental data with a sum of exponential function. Each kinetic trace is normalized to the intensity of the ΔI/I signal at 10-ns delay. C and D, DAS obtained from global fitting of the kinetic transient in the Fud7-P71 (C) and the FN68 (D) strains. For DAS, τ = 77 μs (black diamonds), τ = 357 μs (white squares), offset (black circles). The insets show the details of the DAS in the α- and β-bands of Cyt b₆f absorption for 77 and 357 μs. The DAS are normalized to the value of extrapolated P₇₀₀⁺ absorption bleaching at 430 nm, extrapolated to t_→0 (for time that tends to zero). a.u., Arbitrary units.