Incident Photon Flux (μmol m-2 s-1)Phot

ons

Abso

rbed

and

Util

ized

(μm

ol m

-2 s-1

)

Photons absorbed

Excess

Photons utilized at 25 °C

Photons utilized at 10 °C

Before Damage of PSII Degradation of PSII Following Repair of PSII

LipidsUndamaged PSII

Damaged PSII LHCII

time

Photosystem II Supercomplexes

Free Antenna Complexes

Damaged Photosystem II Monomers

grana stroma lamellae

4 ns

0.5 ns?Immediately After Damage

Before Damage

?Minutes After Damage

4 ns

0.5 ns

Tens of Minutes After Damage

STED beam 730 nm

Excitation beam660 nm

x-axis

y-axisSample

Fluorescence680-720 nm

Excess Sunlight

250 500 750 1000 1250

Photons Utilized Sunlight

250

500

750

1000

1250

Incident Photon Flux (μmol m-2 s-1)

Phot

ons

Abso

rbed

and

Util

ized

(μm

ol m

-2 s-1

)

Without qE With qE

Laser pulse

Laser pulse

DetectorPhotosynthetic Sample

Photosynthetic Sample

Fluorescence Photons Detector

Shutters

We can digitally control when the measurement is made to measure changes in energy transfer as different conditions areapplied to the sample