Fig. 6.
Initial increase of fluorescence yield (O–I 1 rise) in a dilute suspension of Chlorella (300 μg Chl/L) induced by 440-nm AL with 2,131 μmol quanta/(m2 s) in presence of FR background light. Dashed yellow lines indicate F o-level (O), assessed during a 50-μs period preceding onset of AL at time zero, and the I 1-level that is determined with the help of a saturating single-turnover pulse (ST) triggered 1 ms after onset of AL (see Fig. 2 for the Fast Kinetics trigger pattern). The slope of the relaxation kinetics is extrapolated to the end of the 50-μs ST. The black line represents the O–I 1 fit curve based on a PS II model which incorporates energy transfer between PS II units and reoxidation of the primary PS II acceptor QA (see text)