What determines if a photon is absorbed?

[Jarfi]

Say it has xnm wavelength. It hits an atom that reflects it, then another different atom absorbs it, why?

Also what determines if particles like free neutrons or some hadrons will absorb a particular wavelength?


Why does gold absorb all wavelength except yellow and why does it also seem to reflect a small portion of the light(shine).

Is the interactiom of photons with atoms and elemental particles well understood and explaind... with some laws. I've tried reading some electrodynamics but haven't gotten as far to see if a photon copulates with a particle or not or why it would.

 

[mfb]

Quantum mechanics. Depending on your favorite interpretation:
- It does not have any deeper reason and happens randomly.
- Both processes happen.
- It depends on (fundamentally unknown) internal states of the particles.

Why does gold absorb all wavelength except yellow and why does it also seem to reflect a small portion of the light(shine).

That is the result of the band structure - gold is a good reflector for most visible light by the way, as most metals.

Is the interactiom of photons with atoms and elemental particles well understood and explaind... with some laws.

It is, the laws are called quantum mechanics.

 

[Jarfi]

Quantum mechanics. Depending on your favorite interpretation:
- It does not have any deeper reason and happens randomly.
- Both processes happen.
- It depends on (fundamentally unknown) internal states of the particles.
That is the result of the band structure - gold is a good reflector for most visible light by the way, as most metals.
It is, the laws are called quantum mechanics.

So basically its mostly quantum mechanical equations... and the explainaition is "this equation says that this light is most likely to be reflected"

 

[mfb]

So basically its mostly quantum mechanical equations... and the explainaition is "this equation says that this light is most likely to be reflected"

Right.