Figure 3

Low-temperature spectra (1.2 K) of the FMO complex from Chlorobaculum tepidum.

(a) Fluorescence-excitation spectra of FMO from an ensemble (red) and three different single complexes (black). All spectra were recorded with an excitation intensity of 12.5 W/cm². The dashed vertical lines indicate the peak positions of the four Gaussians that have been used for fitting the bulk spectrum. For better comparison the spectra have been normalised and are offset with respect to each other. The typical signal strength at the maximum amounts to 400 to 600 counts per second. Each spectrum corresponds to an average of 200 individual spectra recorded with an acquisition time of 19 s each. (b) Fluorescence emission spectra from an ensemble (red) and three different individual FMO complexes (black). The excitation wavelength was 805 nm and the excitation intensity was 250 W/cm². For better comparison the spectra have been normalised and are offset with respect to each other. Each spectrum corresponds to an average of 400 individual spectra recorded with an acquisition time of 5 s each.