fluorescence and ?

[HippocratesX]

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I rread somewhere that when a photon or some high energy is absorbed, it will show fluorescence...and I can't remember the other half of it...if the photon is emitted....does it show color? or some light in a specific wavelength? I'm confused...i know I read this somewhere, but I can't remember where.

Thx for the help !

 

[Phlame217]

Well I am not sure exactly what you're looking for but:
A photon is a particle of high energy so
If it is absorbed, electrons gain energy and jump up level hence the material will emit a fluorescent light.
When those electrons lose their energy, they will give off light in one of the spectrums depending on how excited they were.

 

[rocuronium]

For materials that fluoresce, when photons with a specific frequency are absorbed, other photons with longer wavelengths are emitted.

When electrons lose energy, they emit photons with energy that matches the difference in energy levels.

 

[HippocratesX]

Okay, here is the part that confuses me.

I thought fluorescence is defined as when a molecule absorbs high-energy photon, and re-emits it as a lower-energy photon after a brief period of time (after the electrons excitement wears off from the high-energy absorbed, it will drop back down to lower energy level). When you say "other photons" are released at a longer wavelength, are they not the same photons that were absorbed, then dropped in energy-levels? Or totally separate photons with longer wavelengths? ...so then it follows that The lower the energy of the photon....the longer wavelength it has? WHY? So therefore, emitted photons have longer wavelengths then excitation photons?

Also in terms of fluorescence or some other type of light showing....So then, what is different about the fluorescence if this fluroscence is "showing" as the photon is being re-emitted as a lower-energy photon....and between some other light "showing" at a different wavelength when there is an emission? When does this fluorescence show? when energy is absorbed? or when energy is released?

 

[Kaustikos]

Okay, here is the part that confuses me.

I thought fluorescence is defined as when a molecule absorbs high-energy photon, and re-emits it as a lower-energy photon after a brief period of time (after the electrons excitement wears off from the high-energy absorbed, it will drop back down to lower energy level). When you say "other photons" are released at a longer wavelength, are they not the same photons that were absorbed, then dropped in energy-levels? Or totally separate photons with longer wavelengths? ...so then it follows that The lower the energy of the photon....the longer wavelength it has? WHY? So therefore, emitted photons have longer wavelengths then excitation photons?

Also in terms of fluorescence or some other type of light showing....So then, what is different about the fluorescence if this fluroscence is "showing" as the photon is being re-emitted as a lower-energy photon....and between some other light "showing" at a different wavelength when there is an emission? When does this fluorescence show? when energy is absorbed? or when energy is released?

You can't define a photon as an individual entity, but as a packet of energy. The energy gets absorbed by the electron and it jumps a couple levels (think mario with star power) and then releases the energy as it goes back down. The energy it releases is just enough to go back down. It is THIS energy that causes the light that you see.

And I think what the person meant by that statement is referring to electrons that absorb energy to catapault it to a certain energy level and then ejecting energy as it goes down a certain energy level but not back to its normal level. Honestly, though, I believe that electrons will go back to their normal level and thus the eventual energy emitted is the energy absorbed. But that they can go down energy levels in multiple steps instead of a single step.

I'm not sure what you mean by your last statement, though. Fluorescence is made by the emission of energy from an electron in a higher energy state.

 

[rocuronium]

Remember that longer wavelength means less energy. In my understanding, when a photon is absorbed by a fluorescent material, some of that energy is lost to internal energy of the material. That means that the material will emit a photon with less energy, and therefore a longer wavelength.

I think the difference between fluorescence and other light given off (say from a lightbulb) is that the fluorescent body is a cold body. It isn't emitting energy of its own, but energy that it absorbs.

 

[HippocratesX]

thanks, that was helpful!

What I meant by my last statement or question, is ....what other kind of "stuff" can show when energy is emitted, besides fluorescence? (just generally speaking...?) And if there is some other magnitude of energy or wavelength or whatever...how is it different from fluorescence??

 

[rocuronium]

Energy released can correspond to anything on the electromagnetic spectrum. The difference between them is their frequency/wavelength.

Check out this Wikipedia article:

http://en.wikipedia.org/wiki/Electromagnetic_spectrum