How does the electron come back down in energy level after absorbing a photon?

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Discussion Overview

The discussion revolves around the behavior of electrons in materials after absorbing photons, particularly focusing on how this relates to the color observed in different substances. Participants explore the mechanisms of electron excitation and de-excitation, the role of energy levels, and the differences between solids, liquids, and gases in this context.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants explain that when a material absorbs a photon, an electron moves to a higher energy level, but question what happens to the electron afterward, suggesting that simple re-emission of the same frequency light would not account for the observed color.
  • Others argue that solids do not have orbitals in the traditional sense but rather energy bands, complicating the explanation of electron behavior.
  • A participant notes that the absorption of light can lead to multiple emissions at lower energy levels, potentially resulting in infrared emissions rather than visible light.
  • Discussion includes the idea that the color of halogens can be explained by the energy gap between molecular orbitals, with different halogens absorbing different wavelengths based on their atomic size and energy requirements.
  • Some participants express uncertainty about the applicability of simple atomic models to complex solids and liquids, emphasizing the need for a more nuanced understanding of molecular interactions and energy states.
  • Questions arise regarding the interaction of light with gases and whether their color visibility is influenced by factors such as density and intermolecular forces.
  • Participants challenge the use of the term "orbital" in describing electron behavior in solids, suggesting it may not accurately represent electron movement in complex materials.

Areas of Agreement / Disagreement

Participants do not reach consensus on the explanations for color in materials, with multiple competing views on the role of electron energy levels, the validity of orbital models, and the mechanisms of light absorption and emission.

Contextual Notes

There are limitations in the discussion regarding assumptions about energy levels, the complexity of molecular interactions, and the definitions of terms like "orbital" in different contexts. The discussion reflects a range of perspectives on these topics without resolving the underlying complexities.

  • #31
BVirtual said:
Even humans disagree on what frequencies are in each "color NAME BAND." Most 'city' people see 5 greens or so, while native tribes living in the forest will name more than 20 green colors by different names, even over 30 different greens. And each member of the same tribe will have agreement between them.
Which is a very good reason not to use colour as experimental data (except in [Edit: colourimetric ] applications). However would the vital relationship E = hf have been found if the experimenters (physicists) had tried it with rainbow colours? The title of this forum has the word Physics in it so we are aiming to promote Physics and not easy alternatives. The colours are, of course relevant and useful for descriptions but not for theory. If you don't find theory important then stick with colours and avoid trying to 'educate' other people about Physics. It really doesn't help them.
 
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  • #33
  • #34
Yes. PF is a website with policies for each of each of its Forums to match the target audience that is desired by the Moderators. Some PF Forums are homework help where adherence is demanded to textbook and citation references in specialty fields of physics. Other Forums are for professionals within the specialty field. These Forums must promote posts with insight to the proper conceptual understanding within that specialty field. Thus, your desire to promote quantitative analysis using frequency over color. A good thing for professionals.

I never thought that someone might use "color names" for quantitative analysis. Never occurred to me, until this thread. I was glad when you mentioned your context of quantitative analysis. That was the turning point in this dialogue.

For me it is a given that analysis with mathematical precision is done with numbers, not conceptual words.

Where qualitative analysis is mostly word based. Color names can be accepted, but only roughly.

It has been a real pleasure for me SophieCentaur to dialogue with you in this thread, as you are able to have a productive dialogue that includes correcting both objective and subjective misunderstandings. A rare skill.
 
  • #35
BVirtual said:
Thus, your desire to promote quantitative analysis using frequency over color. A good thing for professionals.
This suggests to me that you just don't want to get your hands dirty with 'actual maths'. I can safely say that no advance in Physics has ever ben achieved with arm waving, non-quantitive thinking. If you want to be listened to seriously in these matters or to have understanding you will need to be prepared for calculations and formulae. Your "professionals" are just genuine (or aspiring) Scientists.
The very least you can do is to use terms that are appropriate for any message you want to get across. Do not confuse the result (observed colour, for instance) with any 'explanation' in terms of Physics you may feel you have.
 
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  • #36
sophiecentaur said:
Which is a very good reason not to use colour as experimental data (except in [Edit: colourimetric ] applications). However would the vital relationship E = hf have been found if the experimenters (physicists) had tried it with rainbow colours? The title of this forum has the word Physics in it so we are aiming to promote Physics and not easy alternatives. The colours are, of course relevant and useful for descriptions but not for theory. If you don't find theory important then stick with colours and avoid trying to 'educate' other people about Physics. It really doesn't help them.

I hate to break it to you, but color (even by eye) is routinely used in pretty sensitive analytical chemistry techniques. Color can change a lot over pretty narrow concentration ranges. Theory can be important to tell you why the iodine-starch complex looks blue, but at the end of the day if you're doing a redox titration to figure out the concentration of something you're looking for that blue color to show up.
 
  • #37
ketoenol said:
I hate to break it to you, but color (even by eye) is routinely used in pretty sensitive analytical chemistry techniques.

I hate to break it to you, but...

sophiecentaur said:
(...) (physicists) (...) Physics (...) Physics (...) Physics (...)
 
  • #38
ketoenol said:
I hate to break it to you, but color (even by eye) is routinely used in pretty sensitive analytical chemistry techniques. Color can change a lot over pretty narrow concentration ranges. Theory can be important to tell you why the iodine-starch complex looks blue, but at the end of the day if you're doing a redox titration to figure out the concentration of something you're looking for that blue color to show up.
Just what is your point here? Can you show me just one formula in which 'colour' is used in any other study but colour analysis / synthesis? What are you trying to defend?

What number is associated with the blue colour which indicates the presence of starch. I could expect the numbers out of a colorimeter might be used but we're not dealing with Physics in that case.

Of course we all use the terms "Red Shift" and "Blue Shift" in astronomy but could you possibly say how those two observable effects could be used to find the distance or speed of a departing (or approaching) galaxy can be used. Your photons, in this case, tell us nothing more than a perceived colour. ("by eye", as you say).
 
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