Figure 1.9. Absorption spectra for the four types of chlorophyll found in photosynthetic organisms with respect to the visible spectrum. Chlorophyll d and f are found in a cyanobacteria which allows it to utilise infrared light between 700-750 nm, beyond the range normally absorbed by photosynthetic organisms. The chlorophylls are dissolved in methanol which alters their spectra compared to in vivo. The extinction coefficients for the long wavelength peak of each chlorophyll are: Chl a 665.5 nm 71.4 L mmol-1 cm-1, Chl b 652 nm 38.6 L mmol-1 cm-1, Chl d 697 nm 63.7 L mmol-1 cm-1, Chl f 707 nm 71.1 L mmol-1 cm-1. (Based on Chen and Blankenship, Trends Plant Sci 16: 427-431, 2011; Li et al., BBA Bioenergetics, 2012; Porra et al., BBA Bioenergetics 975: 384-394, 1989).