Fig. 3.

a Spectral intensity of 4 mM Mb-CO in 25 mM phosphate buffer pH 7.0 measured in the flow channel of the micro mixer. The very weak absorption of the bound CO at 1,943 cm⁻¹ was detectable even in the single beam spectrum (see inset for the zoom-out). b Absorption spectrum of the aqueous Mb-solution with the IR spectrum of buffer solution as reference. The short path length of the microcell allows for the clear detection of the amide I and amide II absorption bands of the protein backbone