what makes materials transparant?

[ソーナノ]

I hope this is not considered spam as I have posted this elsewhere on the forum but wasn't sure of the right place for it. sorry if it is.

 

To the best of my understanding materials are opaque when the energy of the photons are absorbed by the electrons raising them to the next energy level within the atom/molecule. This energy is then given off as vibrations, heat or as another photon.

 

please correct me if I am wrong thus far.

 

I do not know why this occurs in some materials and not others, I think it's because in opaque materials the wavelength of the electrons match those of the photons in coloured materials and in black materials all the wavelengths of visable light are matched.

 

however this makes no sense to me as surely white materials (not absorbing any but reflecting it) and transparant materials would be the same.

 

so what makes some materials reflect light and some let it through unaffected (or slightly refracted)?

[insane_alien]

the wavelengths of the electrons do not affect the absorbtion of a photon(at least not in the way you think) it is the energy gap between orbitals. if this energy difference correponds to the energy of the photon it can be absorbed by the electron. if not then the photon will not be absorbed.

[ソーナノ]

so if this energy difference does not correpond to the energy of the photon then light will pass straight through? what about white paper?

Is this because in white paper the photons are absorbed but simply re-emitted imediately, unlike in water where they are not absorbed?

 

 

thankyou very much by the way alien.

[YT2095]

Paper`s easy even I know this one, Bits of Wood Fiber get in the way!

 

seriously though, there Is some truth in that, Paper is an aggregate of many different materials, unlike Glass or or some plastics which are mainly One type of molecule sometimes arranged as a Crystaline form.

if you were to take apart paper into INDIVIDUAL molecules and put like with like and then bond them, you would likely find that light would indeed pass though each sheet at a time.

[Klaynos]

Before I answer, what level of physics and maths are you at? Because the true physical answer to this is quite complicated and before I explain things in terms of the maxwell equations and probably the Drude model, I'd like to know whether you'll understand the maths.

 

Electron interactions are the most important thing though.

[ソーナノ]

Thankyou very much for all your suggestions, I have managed to grasp the concept though and I can now get my head around the equasions.

 

A very interesting suggestion though that opaque materials may be transparent if you broke them down further.