Figure 8.

The open-band coherence spectra of the ferric state of CBS at different pH (as in Fig. 6). The pump/probe excitation wavelength is at 425 nm. The left panels show the oscillatory components (circle) and the LPSVD fits (solid red line). The LPSVD component corresponding to the strong γ_a mode at ~40 cm⁻¹ and the phase is also shown (blue solid line). The right panels show the corresponding amplitude of the power spectra. At pH 8 and 9, the modes at ~40 cm⁻¹ (γ_a) and ~90 cm⁻¹ (γ_c) are seen to dominate. When the pH is decreased to ~ 7, a mode at ~75 cm⁻¹ (γ_b) appears and the mode at 90 cm⁻¹ minimizes or disappears. A further decrease of pH to 6, reveals again the strong modes at ~40 cm⁻¹ (γ_a) and ~90 cm⁻¹ (γ_c).