DELAYED FLUORESCENCE FROM <i>CHLORELLA PYRENOIDOSA:</i> EFFECT OF BACKGROUND ILLUMINATION*

Abstract

Abstract— –With background illumination the delayed fluorescence intensity from Chlorella pyrenoidosa observed at 1 msec following a flash of light is greatly increased. It is shown that the background illumination makes a photosystem II product that increases the delayed fluorescence yield and decays in the dark with second order kinetics. The delayed fluorescence observed at 1 msec appears to be more closely related to the primary energy conversion act than delayed fluorescence observed at longer times which is more indicative of electron transport chemical activity.