Fig. 2.

Steady-state RR and TR³ spectra in the high-frequency range of ferrous WT FixLH, for the oxy complex (spectra a–c), CO-bound complex (spectra d–g), and deoxy form (spectra h and i). Spectra a, d, and h are ground-state spectra recorded with cw excitation at 441.6 nm. Spectra b, e, and i are ground-state spectra recorded with subpicosecond excitation at 435 nm, when the pump pulse arrived 5 ps after the probe pulse (Δt = −5 ps). Spectra c, f, and g are difference TR³ spectra, at Δt = 2 ps (spectra c and f) and 20 ps (spectrum g).