Unexpected light from some reactions

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    Light Reactions
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Discussion Overview

The discussion centers on the unexpected emission of light observed during reactions involving sodium hydroxide and various other substances, including water, Triton X-100, and formaldehyde. Participants explore potential mechanisms behind this phenomenon, considering both chemical interactions and experimental conditions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Leopoldo Silvestroni describes experiments showing light emission during reactions with sodium hydroxide and other molecules, noting that the mechanism for this emission remains unclear.
  • Some participants suggest using a spectrometer to analyze the emitted light's frequencies, potentially linking them to specific series such as the Balmer series.
  • One participant mentions that the emitted light is primarily in the green-blue region, as detected by a photomultiplier tube.
  • Questions arise regarding whether the total light intensity corresponds to the sum of individual reaction intensities and whether the reactions are exothermic.
  • It is noted that light emission occurs even when potassium hydroxide or barium hydroxide is used instead of sodium hydroxide, with no light produced in those cases.
  • Another participant points out that light emission also occurs when mixing hypochlorite and sodium ascorbate solutions, despite no apparent heat production.
  • Participants discuss the importance of conducting experiments in absolute darkness to avoid interference with measurements.

Areas of Agreement / Disagreement

Participants express various hypotheses regarding the light emission, but no consensus is reached on the underlying mechanism or the relationship between the reactions and the observed light. Multiple competing views and uncertainties remain present throughout the discussion.

Contextual Notes

Some limitations include the dependence on specific reactants and conditions, as well as the unresolved nature of the mechanisms behind the light emission. The discussion also highlights the need for further experimental validation to clarify the observations.

leosilv
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dear all,
in a series of experiments on the interaction between sodium hydroxide and other molecules such as water, Triton X-100, formaldehyde and others, we found emission of light. Besides the formaldehyde-NaOH interaction, i.e. the Cannizzaro reaction in which some intermediates may form undergoing highly energetic transitions, we have no useful ideas of the mechanism reponsible for such light emission. Our equipment is insensitive to thermophotons, so the exothermicity of the above reactions as the primary source of measurable photons should not be directly involved. Aiming to go more in depth into the aforementioned phenomenon, please consider this post a call for suggestions and/or partnership.
thanks,
Leopoldo Silvestroni
 
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could you use a spectrometer to determine their frequencies and thereby what series they might belong to baumann. lyman...? Maybe that would help determine the chemical bond that was creating the light.
 
jedishrfu said:
could you use a spectrometer to determine their frequencies and thereby what series they might belong to baumann. lyman...? Maybe that would help determine the chemical bond that was creating the light.

I don't know much about physical chemistry. What is the baumann series? Do you mean Balmer series?
 
jedishrfu said:
could you use a spectrometer to determine their frequencies and thereby what series they might belong to baumann. lyman...? Maybe that would help determine the chemical bond that was creating the light.

Roughly, emitted light is in the green-blue region, as assessed by a photomultiplier tube close to the reaction vessel with (broad band) thin plastic filters in between
 
Have you tried removing substances to see if you get the same behavior with fewer reactants?
 
Reptillian said:
Have you tried removing substances to see if you get the same behavior with fewer reactants?

yes. water-NaOH, water-TritonX100, formaldehyde-NaOH are some examples. Light was produced in all the above reactions, though with different intensities (photons per sec)
 
Is the total light intensity equal to the sum of the intensities from the individual reactions? I'm assuming these are exothermic reactions? If so, could this be due to increased radiation (blackbody) from the increase in temperature?
 
I assume that all of these experiments were conducted in absolute darkness?
 
pa5tabear said:
I don't know much about physical chemistry. What is the baumann series? Do you mean Balmer series?

Yes balmer series, my bad memory, sorry.
 
  • #10
Reptillian said:
Is the total light intensity equal to the sum of the intensities from the individual reactions? I'm assuming these are exothermic reactions? If so, could this be due to increased radiation (blackbody) from the increase in temperature?

I'm referring to individual reactions only. The "simplest" example is dropping water onto solid NaOH. Which excited intermediates relaxe with photon emission in our spectral window? (our photomultiplier tube has a 330-550nm spectral sensitivity).
Note: when potassium hydroxide or barium hydroxide are substituted for NaOH, NO light is produced.
Light emission comparable to the above also occurs in the more complex and intermediate-rich formaldheyde-NaOH reaction (i.e. Cannizzaro's reaction).
Moreover, light emission is also produced upon mixing hypochloride and sodium ascorbate solutions, a reaction occurring without apparent heat production.
 
  • #11
chemisttree said:
I assume that all of these experiments were conducted in absolute darkness?
Ground signal from our apparatus is always below 30-50 photons per sec. The cited reactions give a photon output of even dozens of thousands of photons