Photon Systems Instruments FluorPen FP 110 - Page 17

© PSI (Photon Systems Instruments), spol. s r. o.
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Setting the optimal intensities of pulses:
Flash Pulse setting
The optimum value of Flash pulse can be determined with QY measurement as shown in Fig.6 below. Before performing
QY measurement it is recommended to set the intensity of Super pulse to 80 %.
Please note that QY measurement should be performed with dark adapted sample, therefore the same sample (position
on the leaf) should not be used more than once unless dark adaptation follows the first measurement. The
recommendation is to use a new sample (new area on the leaf) for each QY measurements.
F
0
increases linearly with growing intensity of the Flash pulse.
The Flash pulse setting recommended by manufacturer is 30 %. One can increase the intensity of Flash pulse for samples
with very low chlorophyll density. However, it should be noted that high intensities of Flash pulse can cause undesirable
“actinic effect” as higher intensity High Flash pulse will initiate the photochemistry. Changes in the Flash pulse will affect
F
0
and the QY value will be lower.
The optimal Flash pulse intensity is that at which the highest value of QY is reached. This can be easily determined on one
leaf by measuring QY in few different spots with different flash pulse settings. See (Fig. 6) below. In this example the
optimal flash pulse setting is 30%.
Fig. 6 QY measurement performed with different intensities of Flash pulse. Optimal setting is highlighted in red rectangle.
Super Pulse setting
To determine the optimal intensity of Super pulse is to perform OJIP measurement with different Super pulse settings.
Please note that OJIP measurement should be performed with dark adapted sample. New sample (new section of the same
leaf) should be used for every measurement as exposure to super pulse will change photochemistry of the leaf in that
section.
The Super pulse setting recommended by manufacturer is 80 %.
When performing the OJIP measurement with different intensities of Super pulse the F
v
/F
m
value will stop increasing when
the optimal level has been reached for the samples used (Fig. 7 and Fig. 8).