LED - 660nm + 730nm - Emerson effect = WtHeck :P

Kassiopeija said:

Here in this diagram you can see the differences in excitation between the two photosystems:
View attachment 4728806
From "Photobiologie" by L. O. Björn

The PSI drop @ 652nm is created by Chlorophyl-b - which mostly distributes energy towards PSII.
That basically means that 660nm reds would not be sufficient alone to create a better electron-flow (or: to do away with that PSI bottleneck).

If one wants to get the idea, one just needs to look at the suns immense inclusion of red, darkred (FR/IR) to see, why alot of LED spectra are, sort of, incomplete - or better: "in development" .
Well, the new Samsung lm301h-ONE chip did muster up in that regard a bit... (also on green, but that is an entire different story... )

Click to expand...

thank you for the tech talk! i have spent to much time studying lower frequency UV that i am behind on my studies of DR/FR/IR. there is a mystery to me still in what the fuck is IR truly...
Is it heat? Does it make heat? Some say that it is a photonic particle of light which engages by impact the molecular vibrations that initiate thermal radiation. But Nikola felt that the idea of a light particle was foolishness. So... what the fuck is IR? It’s not a wave, it’s not a ray. It’s not some wave that pretends to be a particle when we look at it. It’s not light thus cannot be a photon of light causing thermal vibrations... it is not a causal disruption of waves upon the aether fluid either... it’s something else

I already hear the electromagnetic wave responses but it’s not that if electrons are fictional...

...but mainly, i hear rumors of adding IR to your garden... this or that light has IR diodes... are people just confusing IR with FR? or is there some benefit to the plants in “our” community garden from IR exposure?
(crosses fingers, hopes to learn that IR triples quality)

elibaltutiimaidumituti said:

thank you for the tech talk! i have spent to much time studying lower frequency UV that i am behind on my studies of DR/FR/IR. there is a mystery to me still in what the fuck is IR truly...
Is it heat? Does it make heat? Some say that it is a photonic particle of light which engages by impact the molecular vibrations that initiate thermal radiation. But Nikola felt that the idea of a light particle was foolishness. So... what the fuck is IR? It’s not a wave, it’s not a ray. It’s not some wave that pretends to be a particle when we look at it. It’s not light thus cannot be a photon of light causing thermal vibrations... it is not a causal disruption of waves upon the aether fluid either... it’s something else

I already hear the electromagnetic wave responses but it’s not that if electrons are fictional...

...but mainly, i hear rumors of adding IR to your garden... this or that light has IR diodes... are people just confusing IR with FR? or is there some benefit to the plants in “our” community garden from IR exposure?
(crosses fingers, hopes to learn that IR triples quality)

How does Infrared Relate to heat?

I never understood the relationship between Infrared and Heat. Is IR emitted when heat is generated, is heat generated when IR is made, and how do the two relate?

physics.stackexchange.com

Click to expand...

Yes it can get confusing with light, as there are separate physical theories needed to describe how it behaves - either as wave or particle.
For example, if we want to explain why the sky is blue, or if we run light through a prism - and subsequently split the light into different seamless colors - we need the wave-theory.

For photosynthesis, which is quantum-driven, we need to look at light as being particle-based - that is, one light beam is 1 photon - that has always the speed of light, and a frequency/ wavelength that differs. The frequency/ wavelength is basically the only thing that makes "light" differently - the guys at the link you've posted already explain that perfectly.

Longer wavelength equates to a lesser frequency resulting in a photon that holds lesser energy.

So when we say electromagnetic radiation, or photons, or light - visibly or not, it's always the same, just at another wavelength/frequency/energy-state.

Some of the confusion of UV/ Light/ PAR/ FR/ IR is because these distinctions are MAN-MADE - and arbitrary - and they do differ occasionally from scientific field to field, even though using the very same *word* [!].

For example, in space technology UV-C is electromagnetic radiation/ photons ranging from 100-200 nm (wavelength), UV-B is 200-300 nm, and UV-A is 300-400 nm.

But earth's atmosphere "swallows" some of these wavebands so down on the ground we are left with changed spectrum, and it does make sense to use a different categorization of these words (UV, "light", IR).


Grossly speaking:
UV - 400nm
(Visible) Light: 400-700nm (PAR)
IR - 700nm up to several thousand nm.

You see, the term "light" is already based on our own eye's perception...:


Previously, scientists falsely believed plants can only do photosynthesis with this "visible light". In truth, it's from 380nm up to 780nm, although the region of 750nm to 780nm is only very inefficiently used.

Proof of FR/IR being able to drive photosynthesis:


Plants do also have different responses to different wavelengths, different wavelengths appear in different colors, the way how they interact with the molecules in the air or matter changes (esp. water, bio-matter, and various air molecules are of importance here), and thus it makes sense to make some further differentiation:
UV-C - 100-280 nm
UV-B - 280-315 nm
UV-A - 315-380 nm (or: -400 nm)
PAR:
N-UV - 380-420 nm (near UV - it's actually photosynthetically available, differentiating it from, say 340 nm UVA)
Blue - 400-500 nm (this can be split into several colors as well, esp. violet, blue, cyan)
Green - 500-600 nm (can be split into green, yellow...)
Red - 600-700 nm (can be split into orange, red, far-or deepred)
Farred - 700-750 nm or -780 nm
IR - from 750 or 780 nm up to several thousand.

So I'm using FR/IR sometimes synonymously because the FR light actually behaves a lot like IR light in some ways - it rather penetrates through leaves, but the region has many more qualities or effects on plants.


(^^ note the peak/gap around 550nm "green-color" in both diagrams)

The phytochrome P-fr receptor absorbs heavily from 720-740 nm (depending on conversion state)

(some sources suggest mainpeak @ 718nm)

(tbc next post as I cannot upload more pics...)

Photosystem I is relatively more excitated than PSII with light ranging from 680-750 nm.

Photosynthesis stops absolutely @ 780nm (in landplants) - but this is is based on a number of factors - esp. temperature.

It's also quite hard to measure as there are various methods involved (fluorescence-imaging, O2-evolution measurement, measurement of plant development & harvest mass) - but none of these methods are 100% accurate as there are several complicated systems intertwined which affect each other. For example, is the increased biomass-acquisition of plants under supplemented FR light due to the P-fr "hormone" response, from increased photosynthesis, from beneficial side-effects (such as increased temperature driving metabolism...), presently unknown factors [!], (<-- most likely all of them, but at what relative strength..?!)

Photons can interact with matter in a lot of different ways - this is dependent on the wavelength, the matter itself (even the angle with which the photon hits...); example:


UV usually has so much energy that when it hits bio-matter, it gets absorbed and drastically heats up this matter (causing "vibration" of these atoms, better: disordered movement). But when UV hits snow or ice - it gets mostly reflected. That is, it just hits an electron, pushes it a bit away, and the photon then flies away in another direction ("Compton-effect").

When visible light hits bio-matter, that is, long chains of carbon that are saturated with oxygen and hydrogen, it initially passes it through. But there are a lot of pigments present in said bio-matter which may absorb specific individual wavelengths and these are mostly caused by the implementation of larger molecules in said bio-matter - for chlorophyll that would be 1 magnesium atom surrounded by 4 nitrogen atoms.

But when such a photon is absorbed the single atom gets heated up by the photon by approx. +20.000K locally but since that atoms is usually part of a huge molecule-complex that heat swiftly distributes throughout the system and averages out....

FR/IR in a lot of cases is unaffected by pigments and can pierce deep in or through bio-matter, occasionally heating up these molecules, basically just shines through and don't interact in such a way as being absorbed fully - they penetrate through, get deflected, or better: get absorbed and then send out again (in a slight lesser energy-state - or: longer wavelength) and this is the reason why "Nightvision" or IR biomatter telescopy works so well...
Actually, that's been worded rather poorly... it's more like solid matter has a tendency to release IR photons as a means to release energy into the environment - it has to do with the energy-state of the electrons flying in the outer atom orbitals, they release photons as a means to go into a lower energy-state:

Kassiopeija said:

Yes it can get confusing with light, as there are separate physical theories needed to describe how it behaves - either as wave or particle.
For example, if we want to explain why the sky is blue, or if we run light through a prism - and subsequently split the light into different seamless colors - we need the wave-theory.

For photosynthesis, which is quantum-driven, we need to look at light as being particle-based - that is, one light beam is 1 photon - that has always the speed of light, and a frequency/ wavelength that differs. The frequency/ wavelength is basically the only thing that makes "light" differently - the guys at the link you've posted already explain that perfectly.

Longer wavelength equates to a lesser frequency resulting in a photon that holds lesser energy.

So when we say electromagnetic radiation, or photons, or light - visibly or not, it's always the same, just at another wavelength/frequency/energy-state.

Some of the confusion of UV/ Light/ PAR/ FR/ IR is because these distinctions are MAN-MADE - and arbitrary - and they do differ occasionally from scientific field to field, even though using the very same *word* [!].

For example, in space technology UV-C is electromagnetic radiation/ photons ranging from 100-200 nm (wavelength), UV-B is 200-300 nm, and UV-A is 300-400 nm.

But earth's atmosphere "swallows" some of these wavebands so down on the ground we are left with changed spectrum, and it does make sense to use a different categorization of these words (UV, "light", IR).
View attachment 4729131
View attachment 4729125
Grossly speaking:
UV - 400nm
(Visible) Light: 400-700nm (PAR)
IR - 700nm up to several thousand nm.

You see, the term "light" is already based on our own eye's perception...:
View attachment 4729117

Previously, scientists falsely believed plants can only do photosynthesis with this "visible light". In truth, it's from 380nm up to 780nm, although the region of 750nm to 780nm is only very inefficiently used.

Proof of FR/IR being able to drive photosynthesis:
View attachment 4729123

Plants do also have different responses to different wavelengths, different wavelengths appear in different colors, the way how they interact with the molecules in the air or matter changes (esp. water, bio-matter, and various air molecules are of importance here), and thus it makes sense to make some further differentiation:
UV-C - 100-280 nm
UV-B - 280-315 nm
UV-A - 315-380 nm (or: -400 nm)
PAR:
N-UV - 380-420 nm (near UV - it's actually photosynthetically available, differentiating it from, say 340 nm UVA)
Blue - 400-500 nm (this can be split into several colors as well, esp. violet, blue, cyan)
Green - 500-600 nm (can be split into green, yellow...)
Red - 600-700 nm (can be split into orange, red, far-or deepred)
Farred - 700-750 nm or -780 nm
IR - from 750 or 780 nm up to several thousand.

So I'm using FR/IR sometimes synonymously because the FR light actually behaves a lot like IR light in some ways - it rather penetrates through leaves, but the region has many more qualities or effects on plants.
View attachment 4729124
View attachment 4729116
(^^ note the peak/gap around 550nm "green-color" in both diagrams)

The phytochrome P-fr receptor absorbs heavily from 720-740 nm (depending on conversion state)
View attachment 4729140
(some sources suggest mainpeak @ 718nm)

(tbc next post as I cannot upload more pics...)

Click to expand...

Go in your growroom using green light, they aren't sensible to green light because plants are green... AHAHHAHAHA

Have2 said:

Go in your growroom using green light, they aren't sensible to green light because plants are green... AHAHHAHAHA

Click to expand...

Kassiopeija said:

View attachment 4730272
View attachment 4730275

Click to expand...

You're contributing excellent science and knowledge to the table (y)

So wheres trhe builds

2cent said:

So wheres trhe builds

Click to expand...

I added 6 strips of red.. 3x 660 and 3x 730... Same timer though, I may add, MAYBE, a different timer to control the 730s to get the ladies to sleep and try the 13/11... But getting good results atm so... wondering if it's worth the try and expense.

Have2 said:

I added 6 strips of red.. 3x 660 and 3x 730... Same timer though, I may add, MAYBE, a different timer to control the 730s to get the ladies to sleep and try the 13/11... But getting good results atm so... wondering if it's worth the try and expense.

Click to expand...

Nice yeah its mena be crazy both together.
So currently u just run them all the time lights on ye? Seems nuts dont it a few lights does the whole room compared to the grow lights lol. Love how it looks ..haloweeen lights haha

What size is ur room that 6 strips iluminates
Was told 30w for a 5x5 is adequet what strip u running there and what they running at each,?

2cent said:

Nice yeah its mena be crazy both together.
So currently u just run them all the time lights on ye? Seems nuts dont it a few lights does the whole room compared to the grow lights lol. Love how it looks ..haloweeen lights haha

What size is ur room that 6 strips iluminates
Was told 30w for a 5x5 is adequet what strip u running there and what they running at each,?

Click to expand...

10 strips, f-strip 3000k from samsung, gen 3.
Plus 6 reds strips (660/730). Over a 5x5 area... Running at 900-950 PAR at center... ~650 watts total.

2cent said:

Nice yeah its mena be crazy both together.
So currently u just run them all the time lights on ye? Seems nuts dont it a few lights does the whole room compared to the grow lights lol. Love how it looks ..haloweeen lights haha

What size is ur room that 6 strips iluminates
Was told 30w for a 5x5 is adequet what strip u running there and what they running at each,?

Click to expand...

And yes, red are always on even when in veg.

Only have the 730 to try after light goes off to see if I can improve things.

Hi, what follows are excerpts & quotes from

"SOME FACTORS INFLUENCING THE LONG-WAVE LIMIT OF PHOTOSYNTHESIS" by ROBERT EMERSON et al (1957)

plus comments & other data to help de-mystify what hitherto became known as 'the Emerson Effect'; and to shed some light onto his experiments regarding the extension of the 'Red Drop' limitation of light absorption (into the farred) & the increased photosynthetic activity by adding farred light to light of shorter wavelengths.

(For scientists 660nm & 630nm is "red" or "bright red" whereas 700nm & 730nm is used "darkred" indiscriminately, whereas we today conventionally use "farred")

Both (increases photosynthetic activity & the extension of the absorption spectrum into farred/darkred***) is caused by the very same mechanism (= excitation of Photosystem1 over PS2) though the existance of 2 entangled photosystems was not clear to Emerson at that point in time. But his 1957 works (he has 3 others) ultimately prooved this for the first time.

The 'Emerson Effect' is cited around most popular- and non-scientific internet sources as being caused by using 660nm + 730nm wavelengths. Though true, this embezzles on the fact that the 660nm light (which serves the position of the "background light" in his experiments) can be any type of wavelength between the normal PAR range (although Emerson also showed that its effect - of the background light - is reduces the more closer it gets into the darkred/farred light....)

Still, 660nm is commonly used as a general substitute of 'white light' or 'sunlight' because of its high photosynthetic potential & high leaf absorbance - as the various experiments done were on a very thin layer of isolated chloroplasts in vitro, bacteria-culture in vitro (or a single leaf - other experiments)

However, Emerson took the transmittance of darkred, yellow & green light into consideration.

Excerpts illustrating Emerson's experiments:



^^ this is the lamp giving the farred/long-wave light, which was monochromatic.



^^ the steady background light, hitherto "supplementary light" is a broadband mercury-cadmium bulb that has such a spectrum:

and that was adjusted to various strengths to identify, and clear, the "Kok effect" - the removal of background respiration from the photosynthetic activity measurements.


^^ the later this white-light supplementary background light got filtered to control if all the colors (blue, green or red) would serve the needs - they did.
But the effect was most pronounced at regions in which chlorophylls absorb better to account for a higher photosynthetic activity.


^^ here they describe the loss of efficiency of their supplementary light (which is due to Photo System 2 ends its absorption at 680nm "p680"... actually this is only true for the PS2-core - because the complete PS2-LHC (Light-Harvesting Complex = Core + Antennae) also contain a few "darkred chlorophylls" that can absorb light >680nm via phononic energy addition, but the effect is less pronounced as in PS1 and since farred light has a high tendency for transmittance it takes many incidences to cause that....****)


^^ here Emerson clearly states the E. Enhancement Effect via darkred/farred light addition acts on all visible lightspectras.

I've attached the .pdf.
Additional explanation for those who wish to read it fully:
- Emerson attributes a lot of the observed behaviour to differences of chlorophyll A & B, as he didnt know yet of the Z-schematic of the 2 photosystems.
- Alot of light nm numbers are imprecise simply due to the spec's spikes of the cadmium-mercury lamp used
- Some part of his work are a rebuttal of another work that described this phenomenon differently/flawed
- the pictures shown cut-off at red because the enhancement lies within the darkred region. unfortunately increasing the confusion about the sole necessity of red:farred light.

Emerson's work here prooves the wavelengths necessary to create the 'Emerson Enhancement-Effect' is 680-780nm vs PAR<680nm.


(***) another way to say this is:
Because darkred/farred light can be absorbed in the presence of white light - the total photosynthic activity rises equally (more photons absorbed = higher oxygen evolution).
But today we even know that light 680-780nm can drive PS1 selectively, and (via Cyclical Electrone transport) have some very minor effects - even in the abscence of PAR (white) light....

edit2:
(****) the bacteria used only contain the PS1 & 2 cores but not the LHC1 & 2 antennas of landplants

@PJ Diaz
above you find one of Emerson works on the enhancement effect, you may find that interesting as it shows Wikipdia doesn't tell the full story

Kassiopeija said:

@PJ Diaz
above you find one of Emerson works on the enhancement effect, you may find that interesting as it shows Wikipdia doesn't tell the full story

Click to expand...

Thanks, I'll ready through that we I get a chance. I'm a bit behind in some other required reading I have to absorb first.

White supplementary light action spectrum of the Emerson Effect (>690nm):

in
"THE ACTION SPECTRUM OF THE HILL REACTION IN WHOLE ALGAL CELLS AND CHLOROPLAST SUSPENSIONS. (RED DROP, SECOND EMERSON EFFECT AND INHIBITION BY EXTREME RED LIGHT) by RAJNI VARMA GOVINDJEE"

In this thesis was also found a 'negative Emerson Effect' - when light >700nm is very strong relative to the supplementary light.
Couldn't find the reason back then, speculated about "enzyme throttle" but it is actually due to an over-excitation of Photosystem1 over 2. The mechanism enabling the E.E. works both ways, just that PS2 is usually over-excitated (in non-farred enriched white light).

This was the Far-Red source:



Seems like the Emerson Effect is most pronounced by adding dark-red light in the range of 680-720nm, whereas from 740-750nm may act inhibitory to photosynthesis:


>> A 700nm diode would be better suited than the 730nm IMO.

Kassiopeija said:

White supplementary light action spectrum of the Emerson Effect (>690nm):
View attachment 5095093
in
"THE ACTION SPECTRUM OF THE HILL REACTION IN WHOLE ALGAL CELLS AND CHLOROPLAST SUSPENSIONS. (RED DROP, SECOND EMERSON EFFECT AND INHIBITION BY EXTREME RED LIGHT) by RAJNI VARMA GOVINDJEE"

In this thesis was also found a 'negative Emerson Effect' - when light >700nm is very strong relative to the supplementary light.
Couldn't find the reason back then, speculated about "enzyme throttle" but it is actually due to an over-excitation of Photosystem1 over 2. The mechanism enabling the E.E. works both ways, just that PS2 is usually over-excitated (in non-farred enriched white light).

This was the Far-Red source:
View attachment 5095099
View attachment 5095100

Seems like the Emerson Effect is most pronounced by adding dark-red light in the range of 680-720nm, whereas from 740-750nm may act inhibitory to photosynthesis:
View attachment 5095107

>> A 700nm diode would be better suited than the 730nm IMO.

Click to expand...

philosophy say whaaat?

crimsonecho said:

philosophy say whaaat?

Click to expand...

It dawns me now that the Emerson-Enhancement-Effect is separate from the "special far-red chlorophylls", which have several phononic side-bands in the 720-780nm region. These are said to actually slower trapping kinetics but an excitation of either p680 (in the case of PS1 excitonic overflow) or vice versa - and most likely - an excitation of p700 (in the case of PS2 exciton overflow) via the core-chlorophylls directly should result in a very fast trapping time. And that is achieved by using 640-680nm, or 680-720nm photons, respectively, although within these regions lie & overlap many different chl-a/b vibronic side-bands.
Proof:

On the spectral properties and excitation dynamics of long-wavelength chlorophylls in higher-plant photosystem I
"ABSTRACT
In higher-plant Photosystem I (PSI), the majority of “red” chlorophylls (absorbing at longer wavelengths than the reaction centre P700) are located in the peripheral antenna, but contradicting reports are given about red forms in the core complex. Here we attempt to clarify the spectroscopic characteristics and quantify the red forms in the PSI core complex, which have profound implication on understanding the energy transfer and charge separation dynamics. To this end we compare the steady-state absorption and fluorescence spectra and picosecond timeresolved fluorescence kinetics of isolated PSI core complex and PSI–LHCI supercomplex from Pisum sativum recorded at 77 K. Gaussian decomposition of the absorption spectra revealed a broad band at 705 nm in the core complex with an oscillator strength of three chlorophylls. Additional absorption at 703 nm and 711 nm in PSI–LHCI indicated up to five red chlorophylls in the peripheral antenna. Analysis of fluorescence emission spectra resolved states emitting at 705, 715 and 722 nm in the core and additional states around 705–710 nm and 733 nm in PSI–LHCI. The red states compete with P700 in trapping excitations in the bulk antenna, which occurs on a timescale of ~20 ps. The three red forms in the core have distinct decay kinetics, probably in part determined by the rate of quenching by the oxidized P700. These results affirm that the red chlorophylls in the core complex must not be neglected when interpreting kinetic experimental results of PS.

1. Introduction
Photosystem I (PSI) has structure and composition highly conserved among all oxygen-evolving photosynthetic organisms [1–3]. It harbors ~98 chlorophylls a (Chl a) and ~ 22 carotenoids, coordinated by the two largest subunits PsaA and PsaB. Together with the cofactors of the reaction centre (RC), they form a fused core antenna –RC assembly. In green algae and higher plants, the light-harvesting capacity of PSI is enhanced by the attachment of several subunits of light-harvesting complex I (LHCI) to form a PSI–LHCI supercomplex [4,5], a PSI–FCPI supercomplex exists in diatoms [6]. The LHCI complexes of higher plants are present in single copies per PSI and organized as two heterodimers, Lhca1/4 and Lhca2/3 [7], located on one side of the core complex in a half-moon shape; taken together, they bind ~60 Chl a + b and ~ 13 carotenoids [4]. PSI of almost all organisms contains long-wavelength Chl forms, dubbed “red” Chls, absorbing light at wavelengths longer than the absorption of the RC Chls P700 [8], broadening the absorption spectral range. The red forms are characterized by long-wavelength emission, large Stokes shift, large homogeneous and inhomogeneous broadening and unusually high electron-phonon coupling the mixing of excitonic and charge-transfer states [9–13]. The number of the red Chl forms is species-dependent and their emission maxima vary between different organisms in the range of 700 to 760 nm [14,15]. The majority of the low-energy Chl forms in plants have been shown to reside on LHCI [16–20]. However, several authors have reported a range of values regarding the number of red Chls, their energies and distribution in the core complex and LHCI [9,14,17]. Some have hypothesized that red states at the interface between the core and LHCI maybe lost during their biochemical separation [5]. Although red Chls account for only a small fraction (3–10%) of the total absorption cross-section [21], they have sizeable impact on the dynamics of excitation energy transfer (EET) and trapping, as the excitations must be transferred energetically uphill to the RC [22,23]. The excitation dynamics of PSI has been investigated by many workers. Pioneering picosecond fluorescence studies in the 1970s revealed that PSI fluorescence decays in 80 ps or less at room temperature [24,25] but the lifetimes are drastically slower at cryogenic temperatures because of trapping of excitations on long-wavelength Chls [22,26]. Despite the abundance of time-resolved spectroscopy data, the EET and trapping kinetics are still under debate [3,21]. In most organisms, photochemical trapping of excitations in the bulk antenna occurs on a timescale of about 20 ps [14,27–30]. This has been ascribed to reflect predominantly electron transfer in the RC, i.e. trap-limited kinetics [28,31,32] or EET to P700, i.e. transfer-to-trap-limited limited [14,33–37]. Slower components are observed in PSI with higher abundance of red Chls or more red-shifted forms [14], and in PSI–LHCI supercomplexes [23,29,30,38–40]. A fast process of energy equilibration, typically on a timescale of 2–4 ps at room temperature [14,34,41–47] and 4–6 ps at cryogenic temperature [44,48,49], has been assigned to EET from the bulk antenna Chls to the red forms. The spectral changes on this timescale could also be interpreted as arising from excitation of the RC pigments followed by charge separation [28,31,32,50]. In recent investigations of PSI from higher plants, the bleaching of states absorbing around 700 nm observed on a 2–4 ps timescale, was attributed to the RC pigments [30,51]. One of the reasons for such assignment was that the majority of red Chls in plant PSI are located in the peripheral antenna, whereas the species in question was observed in the core. As the red Chls can significantly affect the PSI kinetics, their stoichiometry, energetic properties, and subunit distribution must be taken into account in any informed model. Therefore, in this work we revisited the red Chl content of the PSI core complex and the intact PSI–LHCI from Pisum sativum by comparing their steady-state absorption and fluorescence emission spectra recorded at 77 K. We were able to resolve multiple spectral forms emitting in the far-red region belonging to both the core and peripheral antenna. There are very few low-temperature time-resolved spectroscopy studies on the dynamics of plant PSI [38,52] and none report the detailed kinetics of the isolated core. We recorded the picosecond fluorescence decays of PSI–LHCI and the isolated core complex at 77 K, allowing us to kinetically resolve the different red Chl forms and propose a model for the kinetics of excitation energy equilibration between them."




^^ the last graph essentially illustrates the slower trapping time which does align with Govindjee's "negative Emerson effect" as described in his thesis.

It's funny that the popular Emerson boosters actually cut-out the most interesting wavelength -695nm to create the Enhancement-effect most efficiently. They seems to rather stimulate PS2 & a slower trapping kinetics (although the enrichment of Far-Red into a normal white light spec still effective for intra-canopy lighting & its phytochrome effects.)
But IIRC the precise absorbance-range is, or can be, slightly shifted depending on the systems temperature, so these numbers are not 100% set in stone. I'm gonna have to dig up a few more works on this & also illustrate PS2 to complement/put things into the right contrast.

Kassiopeija said:

It's funny that the popular Emerson boosters actually cut-out the most interesting wavelength -695nm to create the Enhancement-effect most efficiently. They seems to rather stimulate PS2 & a slower trapping kinetics (although the enrichment of Far-Red into a normal white light spec still effective for intra-canopy lighting & its phytochrome effects.)
But IIRC the precise absorbance-range is, or can be, slightly shifted depending on the systems temperature, so these numbers are not 100% set in stone. I'm gonna have to dig up a few more works on this & also illustrate PS2 to complement/put things into the right contrast.

Click to expand...

Fantastic information you have shared in this thread
This begs the question - Why are lighting systems of differing technologies being compared only with the metric of 400-700nm?