Spectra used for calculation of photolysis quantum yield of ferric NP4NO. (A) Spectra of ferric NP4NO at pH 5.6, (B) Spectra of MbCO. In both figures (A) and (B) the red, black and blue lines represent, respectively, the transient absorption spectrum at t = 20 ps, the scaled equilibrium spectrum of the reactant, and the calculated spectrum of the 5-coordinate photoproduct at t = 20 ps.