Interaction of EM waves with matter

[exmarine]

The interaction of light with matter, or EM waves in general, falls into 3 categories: transparent where they pass through, opaque where they are scattered, and shiny where they are reflected. What on the quantum mechanical level about the atoms electrons determines those properties? I think the electrons in metals are very loosely bound, so they can respond almost without resistance to the incoming waves and thus form a reflective boundary condition. Is that correct, and what about the other two?

 

[ZapperZ]

You might want to start by reading this FAQ:

https://www.physicsforums.com/showthread.php?t=511177

Keep in mind that this is a rather naive description of the optical transport properties in matter. However, the important take-home message here is that (i) atoms in solids have a collective behavior that isn't found in isolated atoms; (ii) this collective behavior often governs many of the characteristics of the material that we encounter.

Zz.

 

[chill_factor]

light in solids can do a lot more than that.

1. in semiconductors, it can be absorbed and promote an electron from the valence band to the conduction band, creating an electron-hole pair. in the presence of an external emf these can separate and lead to a current. this is the basis for photovoltaics.

2. they can change frequency in nonlinear effects such as N harmonic generation.

3. optical solitons can be produced

4. light in some solids can actually self focus.

5. photons can gain momentum or lose momentum in scattering processes with molecular vibrational and rotational degrees of freedom, leading to Stokes shifts, which is characteristic of the material and is used in Raman spectroscopy.