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

Click For Summary
SUMMARY

The discussion centers on the behavior of electrons in materials after absorbing photons, specifically how they return to lower energy levels without simply emitting the same frequency light. It is established that when a material absorbs a photon, such as a red photon, the electron moves to a higher energy level, but upon returning, it may emit light at lower energy levels, often in the infrared spectrum. This process involves multiple stages of emission and can lead to color perception that differs based on the material's state (solid, liquid, gas) and the energy band structure rather than discrete orbitals. The conversation highlights the complexity of color origin in halogens and the importance of understanding molecular orbital transitions.

PREREQUISITES
  • Quantum mechanics fundamentals, particularly electron excitation and energy levels
  • Molecular orbital theory, especially for diatomic molecules like bromine
  • Understanding of light absorption and emission processes in materials
  • Knowledge of thermodynamics related to light interaction with matter
NEXT STEPS
  • Explore the Franck-Condon principle and its implications for molecular excitation
  • Research the energy band theory in solids and its differences from molecular orbitals
  • Investigate the spectral differences between gaseous, liquid, and solid states of halogens
  • Learn about Weisskopf-Wigner theory for spontaneous photon emission and its applications
USEFUL FOR

Students and professionals in chemistry, physicists studying light-matter interactions, and material scientists interested in the optical properties of substances.

  • #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.
 
Last edited:
Physics news on Phys.org
  • #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.
 
  • Like
Likes   Reactions: hutchphd
  • #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).
 
  • Like
Likes   Reactions: weirdoguy

Similar threads

  • · Replies 23 ·
Replies
23
Views
5K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 9 ·
Replies
9
Views
8K
  • · Replies 4 ·
Replies
4
Views
3K
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 22 ·
Replies
22
Views
8K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 8 ·
Replies
8
Views
3K