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chief
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[*] posted on 3-4-2009 at 07:37
reactions that emit radiation


There are chemical reactions which mit electromagnetic radiation: Well known are chemical lasers, the emission of light in the H + Cl -reaction and some others.

Now the question: Are there reactions known which emit in the microwave- or RF- region ? Sounds more than probable to me ... ...

Equipment needed: Some broadband spectral analyzer ...
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[*] posted on 3-4-2009 at 12:05


hmmm...h**p://vv vv vv.metafilter.com/77322/A-Review-of-Criticality-Accidents ?
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Sauron
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[*] posted on 3-4-2009 at 14:36


Those are nuclear reactions, globey.

chief is wondering about chemical masers

Wrong sort of radiation.

He is talking radio frequency or microwave.




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Sedit
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[*] posted on 3-4-2009 at 15:07


I dont know if its what your looking for chief but you could always excite ammonia and as it drops back down to ground state you will emit microwaves.




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pantone159
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[*] posted on 3-4-2009 at 15:36


Quote: Originally posted by Sedit  
you could always excite ammonia and as it drops back down to ground state you will emit microwaves.

Yes, I think it is the lone pair flipping back and forth (with the pyramid inverting), which was used in the first maser.
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watson.fawkes
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[*] posted on 3-4-2009 at 18:26


Quote: Originally posted by chief  
Now the question: Are there reactions known which emit in the microwave- or RF- region ? Sounds more than probable to me ...
First, learn the relation E = hν between photon energy and frequency. (That's a Greek nu, not the letter v.) Then compare that with various ionization and bond energies. In short: HF yes, microwave not so much.

Much more problematic for observation is the photon flux. It's proportional to reaction rates. If the reaction isn't quick, your photon flux will be lost in background noise.

So you want high energy bonds breaking and doing so quickly. Please see Energetic Materials.
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not_important
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[*] posted on 3-4-2009 at 18:40


Furthering that, chemical reactions can be considered to be on the order of 1 to 10 eV, the energy of a 2.45 GHz (microwave oven) photon has energy en close 0.0016 eV ; roughly 3 orders of magnitude less.

IR is in the range emitted by warm to hot objects, so any reaction that generated enough heat to raise the reaction mass to 100 C or better is emitting IR; obviously that's black body and not particular wavelengths.

Because these wavelengths have energies equal to or less than that of thermal oscillations, you'll need resonance structures to select some particular wavelength, as already said you're basically looking at chemical reaction pumped masers.
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JohnWW
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[*] posted on 3-4-2009 at 21:08


In the case of visible light emission by chemical reactions, Chief means chemiluminescence, or in the case of biochemical reactions in living organisms, biochemiluminescence. (See Google.com or Wikipedia.com). The latter are mostly reactions between luciferin and the enzyme luciferase in the bodies of nocturnal insects such as fireflies (to attract a mate) and cave glow-worms (to attract prey), and in patches on the skins of certain deep-sea fishes living in almost complete darkness for the same purposes.

Emission of radiation in reactions in the RF or microwave regions entails the emission of photons of much lower energy. Chemical masers emit microwaves, but involve small changes in energy levels of a substance rather than actual reactions. Of course, all exothermic reactions emit radiation in the form of heat at wavelengths in the infra-red, shorter than microwave wavelengths but longer than visible light.
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[*] posted on 3-4-2009 at 23:35


"Chemical Generation and Reception of Radio- and Microwaves" by Buchachenko and Frankevich is the best text that I have seen on the subject. Although the photon energies are negligible compared to bond energies, RF and Microwave pumping of radical pairs can modify their spin behavior and the reaction paths that are available. I stumbled upon this forum for the first time tonight, and my primary interest for the past couple of years has been dynamic spin chemistry, with a particular focus on the microwave induced magnetic isotope effect (MIMIE). Is there anybody here who is familiar with the work of Anatoly Buchachenko?

Attachment: Magnetic Isotope Effect-Nuclear Spin Control of Chemical Reactions.pdf (206kB)
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watson.fawkes
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[*] posted on 4-4-2009 at 08:03


Quote: Originally posted by merrlin  
Is there anybody here who is familiar with the work of Anatoly Buchachenko?
This is great stuff. Thanks for posting.
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Globey
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[*] posted on 4-4-2009 at 09:13


Aah my bad...I see. Cool, you could disrupt cell phones with a microwave "dhorty b0mba" ;)
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[*] posted on 4-4-2009 at 10:24


Quote: Originally posted by watson.fawkes  
Quote: Originally posted by merrlin  
Is there anybody here who is familiar with the work of Anatoly Buchachenko?
This is great stuff. Thanks for posting.


Thanks for the interest. Attached are two more articles. The article by Timmel and Henbest is one of the better discussions of the mechanisms involved in spin evolution. The article by Salikhov and Malin addresses the fundamental mechanisms of spin modification by microwaves. I have noticed that there are a number of people here who have expertise in electrochemistry. My research project is an investigation of spin locking of electrolytic reactions. I have largely finished the system design and I would like to get some opinions on what transition metal complexes would be best suited for study. I will be starting a new topic "spin locking of electrolytic reactions."

Attachment: Some Peculiarities of Spin Dynamics of Geminate Radical Pairs under Microwave Pumping_.pdf (758kB)
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Attachment: A study of spin chemistry.pdf (406kB)
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[Edited on 5-4-2009 by merrlin]
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