An application of a two-dimensional photoncounter for the determination of emission spectra of thermoluminescence from photosynthetic systems

Emission spectra of two components of thermoluminescence from photosynthetic systems were measured using a two-dimensional photoncounter. Application of this detector system enormously improved the signal to noise (S/N) ratio and enabled the determination of an emission spectrum of a specific thermoluminescence component. The B-band emitting at 30°C showed an emission spectrum having a single peak at 690 nm, whereas the Z-band emitting at -160°C showed a spectrum having two peaks, the major band at 740 nm and a satellite band at 690 nm. It was revealed that the longer wavelength component arises from photosystem I and the shorter wavelength component from photosystem II. Light harvesting chlorophyll a/b protein complexes (LHCI and LHCII) were also found to emit the Z-band at 740 and 690 nm, respectively. The advantage of a two-dimensional photoncounter for the determination of emission spectra of weak luminescence from large-surface biological samples is discussed.