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I don't quite understand photon upconversion. Can two or more photons of various discrete energy level packages converge into less photons of greater difference than before between the highest energy level packages and the lowest? In other words, the energy is conserved but can wavelength be tuned as needed?. For practical use, such upconversion is useful because a barrage of photons from waste heat or factory exhaustion can be converted into visible light for illumination in the settlement (or in greenhouse) and microwave -- after some more wavelength tuning -- for heating water. Therefore the basic standalone needs of the settlement are dealt with using wastes.
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For knightdepaix re #26
In the absence of someone more knowledgeable, I will attempt to confirm as much as I can of your post.
My reading of the research report that started this topic (as found by void) tells me that ONLY TWO photons can be combined into JUST ONE output photon. Your description implies the possibility that more than two photons can participate in the accumulation of energy in an atom's electron shells to generate more than one output photon. My reading of the research is that TWO photons can successively pump an electron into a higher energy state, at which point ONE photon is released at a higher energy level.
However, your interpretation of the implications of the research seem about right.
This would be a great time for you to investigate how the research has advanced. Are you willing (and able?) to do that?
The active membership is quite small at this moment, so each member who remains active has the opportunity to take on more responsibility.
Please investigate what has happened since the research void reported was done, and then update this topic!
(th)
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Thank you th. post#27
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Hmm. Still doesn't do what I need. I need a semiconductor laser with a photon energy of 15.85 eV or higher. Tuned for further requirements. The highest energy semiconductor LED that I can find with Google is 5.3441 eV per photon.
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Here is a report on upconversion ... the report itself may refer back to work reported earlier in this topic, or it may be a report on continued work since the earlier reports:
https://www.yahoo.com/news/solar-power- … 27494.html
The first study, led by researchers at RMIT University, Australia's UNSW, and the University of Kentucky, found that low-energy light that's invisible to the human eye can be "upconverted" using oxygen to generate electricity, which could allow solar panels to generate more energy using the same amount of sunlight.
Edit#1: This report deserves a follow up:
https://newsroom.unsw.edu.au/news/scien … l-research
Oxygen breathes new life into solar cell research
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21 JUL 2020 ARC CENTRE OF EXCELLENCE IN EXCITON SCIENCE/UNSW MEDIA
A world-first in light conversion has potential future implications for solar photovoltaics, biomedical imaging, drug delivery and photocatalysis.
and ...
Until now, this had never been achieved beyond the silicon band gap, which is the minimum energy that is required to excite an electron in silicon up to a state where it can participate in conduction. However, ARC Centre of Excellence in Exciton Science researchers, based at UNSW Sydney, have resolved this challenge – and they transformed a familiar foe, oxygen, into an unlikely friend to achieve their goal.
Together with collaborators at RMIT University and the University of Kentucky, the researchers used semiconductor quantum dots (nanoscale man-made crystals) to absorb the low energy light, and molecular oxygen to transfer light to organic molecules.
Usually oxygen is detrimental to molecular excitons, but at such low energies its role changes and it can mediate energy transfer, allowing the organic molecules to emit visible light, above the silicon band gap.
I am particularly interested in this development because the output of a fission reactor is just dumb heat. At present, it is harnessed (in all cases that I know about) by capturing heat flow between a fluid heated by the fission reaction and an outside heat sink. The process is inefficient for a number of reasons, starting with the laws of thermodynamics. Numerous discussions about thermodynamics are archived in this forum.
Note: I found 226 posts containing the word thermodynamics when I asked FluxBB to give me a count.
However, quantum processes are NOT ruled by the rules of thermodynamics, since they take place 100% or not at all.
My guess is that the role of Oxygen atoms in the process described in the article above is at the quantum level.
Edit#2: Here is support for the quantum physics angle:
The efficiencies are still very low, but the scientists have strategies to improve this in the near future.
“This is only an early demonstration, and there’s quite a lot of materials development needed to make commercial solar cells, but this shows us it’s possible,” Prof. Schmidt says.
And lead author Elham Gholizadeh, also of UNSW Sydney, is optimistic about the potential of the work to make a rapid positive impact on the research field.
“As this is the first time we’ve been successful with this method, we will face some challenges,” she says.
“But I’m very hopeful and think that we can improve the efficiency quickly. I think it’s quite exciting for everyone. It’s a good method to use oxygen to transfer energy.
“Violanthrone doesn’t have the perfect photoluminescence quantum yield so the next step will be to look for an even better molecule.”
For SpaceNut ... can you / would you look for a bit more information about the molecule mentioned in that quote?
(th)
Last edited by tahanson43206 (2020-07-22 09:20:54)
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Part of the issue with solar panels is the efficiency of the receiving is with in a color band and not the total spectrum. That is why they are trying different receiver silica to other doping's as the means to absorb other bands that coming into the panels. The pass and receiving of the energy through each layer is how we are able to collect that energy in one panel.
Phot luminescent is usually a phosphorus layer that is excited by high voltage ac much light a florescent light.
Solar panels that are organic can be made with dyes and Violanthrone is an organic compound that serves as a vat dye and a precursor to other vat dyes.
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For SpaceNut re #31
Thanks for the helpful link about the use of Violanthrone as a dye (or a component of a dye). A dye (of course) serves to impart colors to (usually) fabric by selectively absorbing some photons and reflecting others. Apparently researchers have discovered a property of the molecule that allows for photon upconversion in addition to the other well known behaviors.
The goal I am hoping the researchers achieve is the ability to accept thermal energy and convert it cleanly to electric current without going through the normal physical movement of atoms at all.
This discussion triggered a thought I've never had occasion to consider before .... we (or at least I) take if for granted that sunlight causes the surface of materials to heat up. Why?
How does the arrival of a photon in the vicinity of a molecule bound to other molecules in a matrix (ie a solid) cause the molecule to start moving with respect to the matrix, so that the energy of the moving molecule is imparted to other molecules in the matrix?
Edit#1 ... following up ... here is a ScientificAmerican article that explains a mechanism (there are apparently multiple) that causes incoming photon energy to translate into movement of an entire molecule.
https://www.scientificamerican.com/arti … -light-tr/
(th)
Last edited by tahanson43206 (2020-07-22 18:03:45)
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For SpaceNut re #33
Thank you for a set of helpful links for learning about solar cells !!!
In post #32, I asked a more fundamental question ... how is it possible for an arriving photon to cause a molecule to start to move?
https://www.scientificamerican.com/arti … -light-tr/
This article from Scientific American helps to explain part of the process. Apparently there is more than one mechanism, but one is sympathetic vibration of the target molecule upon encounter with a photon having just the right frequency to tune itself to the molecule, which then absorbs the energy from the photon and moves more rapidly inside the bounds of its electrostatic bonds, and (apparently) communicating its increased energy level to its neighbors.
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It starts with https://en.wikipedia.org/wiki/Solar_oscillation aka the sun that in oscillation and continues as the photon strikes the material. As matter even solid has the electrons moving all the time.
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For SpaceNut re #35
Your observation about the universal nature of vibration stayed with me, so when I found this item in the news feed this morning, I decided to take a look at it. The authors are pursuing the theory that intelligence/consciousness arises from the complexity of vibrations, and particularly the mass synchronization of neurons in living creatures.
Your post #35 mentions electrons moving, but I'd like to point out that the nuclei are moving as well. It is the movement of the nuclei that the article I pointed out is considering when a photon contributes energy to a molecule by synchronization with the movement of the atom. Absorption of a photon by an electron that causes the electron to move to a higher shell is NOT what the article about heating of matter by photons was discussing (as I understood the article).
So here is the article about consciousness and vibration:
https://getpocket.com/explore/item/coul … ket-newtab
Our resonance theory of consciousness attempts to provide a unified framework that includes neuroscience, as well as more fundamental questions of neurobiology and biophysics, and also the philosophy of mind. It gets to the heart of the differences that matter when it comes to consciousness and the evolution of physical systems.
It is all about vibrations, but it’s also about the type of vibrations and, most importantly, about shared vibrations.
Tam Hunt is an Affiliate Guest in Psychology at the University of California, Santa Barbara.
Please note that the article ** does ** disclaim any association with hippies!
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tahanson43206 wrote:For Calliban re #158
Thank you for those encouraging looking updates on molten salt reactors!
You are a practicing engineer, so I expect you to be skeptical of unproven research.
That said, are you aware of progress in understanding the quantum process that facilitates intake of heat photons and combining them (through their guided interaction with electron shells in selected molecules) to yield output at a higher energy (frequency) level?
I do not claim to understand much about the physics involved, but I ** am ** hoping the research will yield a practical way to avoid dumping (otherwise useless) heat energy into space, and instead harnessing it (or some part of it) to make useful photons, such as those suitable for capture by photoelectric cells.
There are several posts about this in the forum.
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Sounds like an interesting technology. But there is no escaping entropy. Upgrading photons means taking low grade infrared light and converting it to shorter wavelengths. There is no way that this can work without increasing total entropy. I suspect that the only way you can produce one photon of short wave radiation is by downgrading a number of others which you then have to dump into space. That is the inescapable nature of the universe. Entropy always increases.
reference light in this repost
I promised to provide a scientific determination of whether we would have enough light to grow crops on Mars at 60 deg north, under 5-10m of ice and water. Here is the answer.
Some more detailed discussion of light attenuation properties of water. Photosynthetically available radiation basically corresponds to the visible spectrum 400-700nm. However, the rate of photosynthesis appears to depend more upon the number of photons arriving per second, rather than the total energy. This tends to mean that red light is more significant than blue light in terms of utilisation of energy. Hence, the growth rate and health of plants is a function of Daily Light Integral (DLI). This is measured in mols/m2/day.
https://en.wikipedia.org/wiki/Daily_light_integralThe spectrum of light hitting the Earth's upper atmosphere is provided by the link below.
https://en.wikipedia.org/wiki/File:Sola … rum_en.svgAs you can see, the flux is actually quite flat between 400-700nm, with flux levels between 1.5-2W/m2 per nm. I have chosen a few datum points, to model the attenuation of light by water.
Red (600-700nm): flux ~1.5W/m2/nm
Green (500nm): flux ~1.9W/m2/nm
Blue (450nm): flux ~1.9W/m2/nm
Violet (400nm): flux ~1.7W/m2/nmEach wavelength has its own attenuation coefficient in water. I used the chart below, to estimate attenuation coefficient in water for the datum points that I selected.
https://en.wikipedia.org/wiki/Electroma … _water.pngRed (600-700nm): 0.1-1.0/m
Green (500nm): 0.03/m
Blue (450nm): 0.02/m
Violet (400nm): 0.04/mNotice also from the chart, that ultraviolet light has a very strong scattering cross section in water. This starts at about 0.1/m at the very beginning of the UV spectrum (350nm) and reaches about 5.0/m at 200nm and then 1E7/m at 160nm. I would suggest that it is quite unlikely that UV would be a serious problem on Mars at a water depth of 5m or more. I doubt that you would need to apply any UV blockers to the water or ice surface.
Back to the visible or photosynthetically available radiation (PAR). The fraction of light reaching a depth of 5m can be calculated for each wavelength. As you can see, red light is attenuated most strongly; the green and blue parts of the spectrum experience relatively little attenuation.Red (600-700nm): 0.17
Green (500nm): 0.86
Blue (450nm): 0.9
Violet (400nm): 0.82
UV (350nm): 0.59
UV (300nm): 0.33
UV (250nm): 0.01
UV (200nm): 0.0
UV (160nm): 0.0To determine the effect that attenuation would have on the DLI, I weighted each light wavelength according to its relative flux at the top of the water and its wavelength. So the fraction of DLI present at a given depth can be estimated using the following equation:
F=∑((CA^d)×q×λ)/∑(q×λ)
Where CA is the attenuation coefficient per m, d is the water depth in m; λ is wavelength, q is the flux in W/m2/nm and F is the ratio of DLI at depth, d, compared to the surface. The fraction of DLI still available at depths of 5m and 10m, are 0.667 and 0.55, respectively.
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Entropy (Second Law of Thermo) is why Edsel Murphy of Murphy's Law fame was an optimist. That and the Third Law of thermo.
First Law: you cannot win (easiest way to understand energy conservation)
Second Law: you will always lose (the proof gets clouded by the math of entropy in most texts, but that IS what it fundamentally means)
Third Law: you will always lose BIG-TIME / you cannot get out of the game (most folks have never even heard of this one)
GW
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For Calliban re #160
Thanks for thinking about photon upconversion ...
I'll keep your concern in mind as I try to learn more. It is my understanding that NO energy is lost when events occur at the quantum level.
There is nothing to throw away, if I understand your meaning.
However, as I say, I'll keep your concern in mind.
(th)
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For SpaceNut ...
Thanks for consolidating the Photon Upconversion discussion in the appropriate topic
I am hoping that somewhere along the line this forum will attract a visit by someone who is deeply knowledgeable about quantum physics, and who is interested in the difficulty traditionally trained engineers would naturally have in understanding the processes at work.
It would appear (to my limited understanding) that quantum events happen without loss, unlike non-quantum transitions which ** always ** include loss.
The advantage of quantum level energy pumping is clear enough. What is ** not ** clear (to me for sure) is that it is possible for humans to devise mechanisms that can take low grade thermal activity and convert it to high value photosynthesis of useful molecules.
In re-reading that paragraph, I realize I have missed the problem. Humans have already demonstrated photon pumping at the laboratory level.
What is not yet achieved (and may not be possible) is ** large ** scale application of the phenomena for useful (electric) energy production from low grade thermal sources.
All traditional (non-quantum) energy production from thermal sources depends upon the flow of heat (thermal activity/molecular vibration) to a heat sink.
That is why spacecraft designs that include nuclear power sources include radiators which can dump low grade heat to space, and thus pull thermal activity from the heat source so that energy can be harvested.
Quantum level photon pumping does ** not ** (as I understand it) require a heat sink.
(th)
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Frequency up shift is a function of material resonance of energy summing.
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I thought someone here might like this for this topic:
https://phys.org/news/2021-11-photon-up … ngths.html
Quote:
Doing photon upconversion a solid: Crystals that convert light to more useful wavelengths
I suppose we might hope that the output of a thermal storage device might upconvert to some more useful wavelength.
Done.
Done.
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For Void! Thank you for this significant addition to the topic!
The work reported is certainly encouraging!
It may be too much to hope for, but I ** hope ** that researchers will eventually find an efficient way of converting useless heat output of a fission reactor into high value photons that can deliver electrical current flow directly.
In the example cited, the research team took in green wavelength photons and (apparently) created higher value ones.
Overall, this study brings van der Waals crystals back into the game of PUC as an effective way of creating outstanding solid materials using versatile hydrocarbon annihilators. "The proof-of-concept we presented in our paper is a major technical leap forward in the quest for high-performance PUC solids, which will open up diverse photonics technologies in the future," concludes Dr. Murakami. Let us hope further research in this topic allows us to efficiently transform light into its most useful forms.
Explore further
Efficient photon upconversion at an organic semiconductor interface
More information: Riku Enomoto et al, van der Waals solid solution crystals for highly efficient in-air photon upconversion under subsolar irradiance, Materials Horizons (2021). DOI: 10.1039/D1MH01542G
Provided by Tokyo Institute of Technology
SearchTerm:photon upconversion progress green light
SearchTerm:upconversion photon green light
SearchTerm:green light upconverted
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Recruiting High Value members for NewMars.com/forums, in association with the Mars Society
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The science of optical materials is on going even when used for solar cell construction which is using as much of the absorption of various frequencies of that light that is hitting the target materials. So not surprising that that same science is being applied to shifting the resulting frequency of the light. I have seen this same thing happening with laser color being shifted as well.
Another partial post that applies here
The first thing to understand about light, or electricity for that matter, ultimately "energy" (and photons, aka "light", are quanta of energy), is that it's a combination of perpendicular oscillating electric and magnetic fields, wherein both the electric and magnetic fields are in phase with each other.
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hum the old game of pong on the black and white tv of the era
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This report on Photon Up conversion showed up when I followed a link provided by Mars_B4_Moon, about advances in fusion research.
https://www.spacedaily.com/reports/Kobe … s_999.html
Kobe breakthrough offers blueprint for enhanced photon up-conversion materials
by Riko Saibo
Kobe, Japan (SPX) Mar 19, 2024Researchers at Kobe University have made a significant advancement in the quest for more efficient energy utilization by uncovering a method to merge two low-energy photons into a single high-energy photon. This discovery is pivotal for the next generation of photovoltaic cells, OLED displays, and novel anti-cancer treatments. The team, led by photoscientist Yasuhiro Kobori, has provided critical insights into the molecular dynamics necessary for this process, known as photon up-conversion.
Photon up-conversion, the process of transforming lower-energy photons into a single photon of higher energy, is a key technological goal for enhancing the efficiency of solar cells, improving the performance of OLED displays, and developing new anti-cancer therapies. Despite its potential, the mechanism facilitating efficient up-conversion remained poorly understood, hindering material development. Kobori's research group has now bridged this gap by focusing on the electron spin states of excited molecules within a solid.The study, detailed in The Journal of Physical Chemistry Letters, reveals that for effective photon up-conversion, the electron spin states of two "triplet excitons" must align. This alignment is contingent on the molecules' orientation and their ability to freely transfer energy through varied orientations without proceeding too rapidly, ensuring adequate time for energy interconversion.
The breakthrough came from utilizing a thin-film solid-state material, enabling the observation of magnetic properties of electron spins and generating high concentrations of triplet excitons. This method overcame previous obstacles seen in solution systems, where rapid molecular rotation complicates magnetic property observations, and in conventional solid-state systems, which suffer from low reaction efficiencies.
Kobori's team employed a comprehensive approach, initially observing the electron spin state's temporal evolution in solid-state up-conversion materials. They then modeled the electron spin motion and formulated a new theoretical model linking the electron spin state to the up-conversion process.
This discovery offers a design guideline for creating highly efficient photon up-conversion materials based on an understanding of the microscopic mechanisms involved. Kobori envisions this knowledge facilitating the development of high-efficiency solar cells and expanding into other areas, such as photodynamic cancer therapy and diagnostics using near-infrared light, without damaging human tissue.
Research Report:Efficient Spin Interconversion by Molecular Conformation Dynamics of a Triplet Pair for Photon Up-Conversion in an Amorphous Solid
Related Links
Kobe University
Space Technology News - Applications and Research
Photon up conversion was described as crucial for development of the next generation of solar cells.
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