Fluorescence decay kinetics of chlorophyll in photosynthetic membranes

Abstract

The absorption of light by the pigments of photosynthetic organisms results in electronic excitation that provides the energy to drive the energy-storing light reactions. A small fraction of this excitation gives rise to fluorescence emission, which serves as a sensitive probe of the energetics and kinetics of the excited states. The wavelength dependence of the excitation and emission spectra can be used to characterize the nature of the absorbing and fluorescing molecules and to monitor the process of sensitization of the excitation transfer from one pigment to another. This excitation transfer process can also be followed by the progressive depolarization of the emitted radiation. Using time-resolved fluorescence rise and decay kinetics, measurements of these processes can now be characterized to as short as a few picoseconds. Typically, excitation transfer among the antenna or light harvesting pigments occurs within 100 psec, whereupon the excitation has reached a photosynthetic reaction center capable of initiating electron transport. When this trap is functional and capable of charge separation, the fluorescence intensity is quenched and only rapidly decaying kinetic components resulting from the loss of excitation in transit in the antenna pigment bed are observed. When the reaction centers are blocked or saturated by high light intensities, the photochemical quenching is relieved, the fluorescence intensity rises severalfold, and an additional slower decay component appears and eventually dominates the decay kinetics. This slower (1-2 nsec) decay results from initial charge separation followed by recombination in the blocked reaction centers and repopulation of the excited electronic state, leading to a rapid delayed fluorescence component that is the origin of variable fluorescence. Recent growth in the literature in this area is reviewed here, with an emphasis on new information obtained on excitation transfer, trapping, and communication between different portions of the photosynthetic membranes.

Observation of nanosecond laser induced fluorescence of in vitro seawater phytoplankton

“…Light travel times cannot be the cause, since a 10 ns delay would represent some spatial gap of approxi mately 3 m, which is two to three times larger than the entire apparatus. Such a delay between pump and fluorescent emission has been seen in other work [20] and is common in photosynthetic systems [7,[21][22][23][24][25][26][27], being called delayed fluorescence (DF). It is noted that, with the exception of Ref.…”

Energy Transfer in Trimeric C‐phycocyanin Studied by Picosecond Fluorescence Kinetics

“…1982;Holzwarth et al, 1983b;Suter et al. 1984;Hefferle et al, 1984a;Hefferle et al, 1984b;Gillbro ef ul., 1983;Mimuro et al, 1984;Yamazaki et al, 1984;Switalski and Sauer, 1984;Wong et al, 1981;Holzwarth, 1985;Wehrmeyer et al, 1985;Gillbro et al, 1985;Mimuro et al, 1985;Glazer et al, 1985;Hanzlik et ul., 1985; for recent reviews see Karukstis and Sauer, 1983;Scheer, 1985). These studies support a general scheme, where the excitation energy ~ -.…”

Kinetic and Spectral Resolution of Multiple Nonphotochemical Quenching Components in Arabidopsis Leaves

“…For example, the fluorescence of PSII peaks in the region of 680 to 685 nm, whereas beyond 700 nm, the PSII fluorescence intensity drops to less than 20% of its peak intensity. In contrast, the fluorescence of intact PSI complexes is dominant in the region above 710 nm (Haehnel et al, 1982;Karukstis and Sauer, 1983;Holzwarth et al, 1985;Holzwarth, 1986;Slavov et al, 2008). Thus, the widely used instrumentation measures the NPQ parameters in a region with reduced PSII contribution and relatively high PSI contribution to total fluorescence, despite the fact that NPQ is generally considered to be primarily a PSII phenomenon.…”