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  • 1
    Electronic Resource
    Electronic Resource
    Continuous recording of photochemical and non-photochemical chlorophyll fluorescence quenching with a new type of modulation fluorometer (1986)
    Springer
    Photosynthesis research 10 (1986), S. 51-62 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; fluorescence quenching ; fluorometer ; Kautsky effect ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A newly developed fluorescence measuring system is employed for the recording of chlorophyll fluorescence induction kinetics (Kautsky-effect) and for the continuous determination of the photochemical and non-photochemical components of fluorescence quenching. The measuring system, which is based on a pulse modulation principle, selectively monitors the fluorescence yield of a weak measuring beam and is not affected even by extremely high intensities of actinic light. By repetitive application of short light pulses of saturating intensity, the fluorescence yield at complete suppression of photochemical quenching is repetitively recorded, allowing the determination of continuous plots of photochemical quenching and non-photochemical quenching. Such plots are compared with the time courses of variable fluorescence at different intensities of actinic illumination. The differences between the observed kinetics are discussed. It is shown that the modulation fluorometer, in combination with the application of saturating light pulses, provides essential information beyond that obtained with conventional chlorophyll fluorometers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024185
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  • 2
    Electronic Resource
    Electronic Resource
    Detection of rapid induction kinetics with a new type of high-frequency modulated chlorophyll fluorometer (1986)
    Springer
    Photosynthesis research 9 (1986), S. 261-272 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; fluorometer ; fluorescence quenching ; Kautsky effect ; photosynthesis ; photosystem II
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A newly developed modulation fluorometer is described which operates with 1 μsec light pulses from a light-emitting diode (LED) at 100 KHz. Special amplification circuits assure a highly selective recording of pulse fluorescence signals against a vast background of non-modulated light. The system tolerates ratios of up to 1:107 between measuring light and actinic light. Thus it is possible to measure the “dark fluorescence yield” and record the kinetics of light-induced changes. A high time resolution allows the recording of the rapid relaxation kinetic following a saturating single turnover flash. Examples of system performance are given. It is shown that following a flash the reoxidation kinetics of photosystem II acceptors are slowed down not only by the inhibitor DCMU, but by a number of other treatments as well. From a light intensity dependency of the induction kinetics the existence of two saturated intermediate levels (I1 and I2) is apparent, which indicates the removal of three distinct types of fluorescence quenching in the overall fluorescence rise from F0 to Fmax.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029749
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    Paper (German National Licenses)
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