Fluorescence parameters | Description |
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Fluorescence parameters | Description |
Ft | Fluorescence intensity at time t after onset of actinic illumination |
F50 μsor F20 μs | Minimum reliable recorded fluorescence at 50 μs with the PEA- or 20 μs with Handy-PEA-fluorimeter |
F100 μs and F300 μs | Fluorescence intensity at 100 and 300 μs, respectively |
FJ and FI | Fluorescence intensity at the J-step (2 ms) and the I-step (30 ms), respectively |
FP (= Fm) | Maximum recorded (= maximum possible) fluorescence at P-step |
Area | Total complementary area between fluorescence induction curve and F = Fm |
Derived parameters | |
Selected OJIP parameters | |
F0 ≅ F50 μsor F0 ≅ F20 μs | Minimum fluorescence, when all PSII RCs are open |
Fm = FP | Maximum fluorescence, when all PSII RCs are closed |
VJ = (F2 ms - Fo)/(Fm - Fo) | Relative variable fluorescence at the J-step (2 ms) |
VI = (F30 ms - Fo)/(Fm - Fo) | Relative variable fluorescence at the I-step (30 ms) |
Mo = 4 (F300 μs - Fo)/(Fm - Fo) | Approximated initial slope (in ms-1) of the fluorescence transient V = f(t) |
Sm = ECo/RC = Area/(Fm - Fo) | Normalized total complementary area above the OJIP (reflecting multiple-turnover QA reduction events) or total electron carriers per RC |
Yields or flux ratios | |
φPo = TRo/ABS = 1-(Fo/Fm) = Fv/Fm | Maximum quantum yield of primary photochemistry at t = 0 |
φEo = ETo/ABS = (Fv/Fm) × (1 - VJ) | Quantum yield for electron transport at t = 0 |
ψEo = ETo/TRo = 1-VJ | Probability (at time 0) that a trapped exciton moves an electron into the electron transport chain beyond QA- |
φDo = DIo/ABS = 1-φPo = Fo/Fm | Quantum yield at t = 0 for energy dissipation |
δRo = REo/ETo = (1 - VI)/( - VJ) | Efficiency with which an electron can move from the reduced intersystem electron acceptors to the PSI end electron acceptors |
φRo = REo/ABS = φPo × ψEo× δRo φ | Quantum yield for the reduction of end acceptors of PSI per photon absorbed |
Specific fluxes or activities expressed per reaction center (RC) | |
ETo/RC = (Mo/VJ) × ψEo = (Mo/VJ) × (1-VJ) | Electron transport flux per RC at t = 0 |
DIo/RC = (ABS/RC) - (TRo/RC) | Dissipated energy flux per RC at t = 0 |
REo/RC = (REo/ETo) × (ETo/RC) | Reduction of end acceptors at PSI electron acceptor side per RC at t = 0 |
ETo/CSo = (ABS/CSo) × φEo | Electron transport flux per CS at t = 0 |
TRo/CSo = (ABS/CSo) × φPo | Trapped energy flux per CS at t = 0 |
DIo/CSo = (ABS/CSo) - (TRo/CSo) | Dissipated energy flux per CS at t = 0 |
REo/CSo = (REo/ETo) × (ETo/CSo) | Reduction of end acceptors at PSI electron acceptor side per CS at t = 0 |
Density of RCs | |
RC/CSo =φPo × (ABS/CSo) × (VJ/Mo) | Amount of active PSII RCs per CS at t = 0 |
Performance index | |
PIabs = (RC/ABS) × (φPo/(1 - φPo)) × (ψo/(1 - ψo)) | Performance index (PI) on absorption basis |
PItot, abs = (RC/ABS) × (φPo/(1-φPo)) × (ψEo/(1 - ψEo)) × (δRo/(1 - δRo)) | Total PI, measuring the performance up to the PSI end electron acceptors |