Fig. 5: Comparison of the excitation spectra after different illumination times.

The respective excitation spectra after one (black), two (red), and five (blue) flashes, as well as after continuous exposure to light (green), are shown (d). A shift can be observed with increasing exposure from 1659 cm⁻¹ to 1667 cm⁻¹ (a), from 1555 cm⁻¹ to 1562 cm⁻¹ (b), and from 1184 cm⁻¹ to 1176 cm⁻¹ (c). 1659 cm⁻¹ and 1555 cm⁻¹ represent the amide region of the proteins. 1184 cm⁻¹ is a marker band for protonated 13-cis retinal.