CHAPTER 7 THE MODE-MENU
fluorescence, Fo, and maximal fluorescence, Fm, of a dark-adapted
sample by use of the SET-key
. The thus sampled values are stored
until new values are sampled via SET
. With START a normal
YIELD-determination is carried out and the given Fo- and Fm-values
are maintained. The stored Fo- and Fm-values are used for
determination of the quenching coefficients qP, qN and NPQ (see
menu points 26 and 27). In some applications, in order to obtain
minimal Fo it is advantageous to make use of the ML-BURST
function (see menu point 5).
Coefficients of photochemical quenching,
qP, and non-photochemical quenching, qN,
as defined by the following equations:
26: qP:1000qN:000 (SET)
F: 448 745Y 6.2E 20L
qP=(M-F)/(M-Fo) and qN=(Fm-M)/(Fm-Fo)
In order to obtain the usual values between 0 and 1, the displayed
values have to be multiplied by 0.001. qP is set to 000 if M<F and
qN is set to 000 if M>Fm. qN is set to 1.000 if M<Fo.
Note: M here represents the maximal fluorescence measured by a
saturation pulse in any given light state (normally denoted Fm'),
whereas Fm and Fo are the particular values sampled via menu point
25 after dark-adaptation. The thus determined values of qP and qN
should be considered approximations only, as a possible non-
photochemical quenching of Fo is not taken into consideration.
Parameter describing non-photochemical
quenching defined by the equation:
27: NPQ:1.440 (SET)
F: 448 745Y 6.2E 20L
NPQ = (Fm-M)/M
Note: M here represents the maximal fluorescence measured by a
saturation pulse in any given light state (normally denoted Fm'),
whereas Fm is the particular value sampled via menu point 25 after
dark-adaptation. NPQ has been shown to be closely related to the
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