Figure 4.

Absorption spectra of (a) myoglobin and (b) cytochrome c thin films doped with 0.5 M NaBr before and after exposure to X-ray radiation recorded using the SLS on-axis microspectrophotometer. Several intermediate spectra are shown to highlight the isosbestic point in each system. The arrows show, from left to right, the position of the Soret and α-bands upon X-ray reduction and the 600 nm feature. Sample extracted time courses for (c) myoglobin and (d) cytochrome c showing the changes in absorbance at the three wavelengths of interest versus time (accumulated dose). The upright line on the X-axis indicates the point at which the X-ray shutter was opened; from this point the sample was continuously irradiated.