How do colours work at subatomic levels?

Question

I searched for it but couldn’t get anything.

I know that if some material is a shade of green colour then light of every other wavelength other than that shade is absorbed.

Also that the colour appears due to the visible electromagnetic radiation by de-excitation of electrons.

What I don’t understand is:

Why do electrons keep oscillating between higher and lower states?

Electrons can move from one level to another level by emitting photons of different energy. For example for level 5 to level 1, it can go 5->3->1 or 5->4->3->2->1. So why is the apparent colour consistent?

A blue pigment absorbs yellow light. So electrons absorb yellow light to excite but give off blue when de-exciting for the same transition. How does this hold conservation of energy?

Would there be any observed colour difference if the same light bulb is kept in a blue room with blue objects and then a yellow room with same blue objects?

Thanks for helping.

In: Chemistry

Answer 1

> A blue pigment absorbs yellow light. So electrons absorb yellow light to excite but give off blue when de-exciting for the same transition.

No. A blue pigment absorbs yellow light and *reflects* blue – it doesn’t emit blue.

But the behavior you’re describing, of single discrete energy levels that are constant for each atom and no other means of dispersing energy, only apply to *isolated* atoms. An atom in a low-density gas way out in space does behave that way, and so a 1->4 transition would either go 4->3->2->1 or 4->3->1 or 4->2->1 or 4->1 (emitting higher-wavelength light in the first three cases).

But atoms in materials have other ways to disperse energy. They have internal higher-energy states, centered around things like the spin-orientation of their electrons (although these states tend to decay pretty quickly). They have strong bonds to other atoms in the same molecule that are somewhat ‘elastic’ and can absorb energy by stretching or twisting. (This is how the proteins that detect light in your eyes work – they have a bond that twists when they absorb a photon.) They have weak bonds to the overall structure of their parent material that can do the same. And so on. So an electron can absorb energy but then release it in forms other than photon re-emission.