Thermoluminescence studies on photosynthetic energy conversion. I. Evidence for three types of energy storage by Photoreaction II of higher plants

Thermoluminescence was examined in isolated chloroplasts in the presence and absence of electron acceptors and inhibitors of electron transport, and in digitonin subchloroplast particles. Absence of emission from Photosystem I particles indicated that thermoluminescence originated from energy storage in Photoreaction II. Three distinct glow peaks were observed, suggesting that quantum conversion at Reaction Center II may involve three different types of energy storage with differing stabilization energies. Electron acceptors and inhibitors of electron transport had different effects on the three glow peaks. Although correlations can be drawn between the three storage states of the glow curves and components of delayed light emission at different dark times, we were unable to definitely associate any of the thermoluminescence peaks with delayed light emitted during a particular time-range of dark decay.