How do quanta behave interacting with electrons at the band gap?
If the electron at the band gap is able to absorb the quantum, it will jump from the conduction band to the valence band, the result is a decrease in conductivity. The same electron will re-emit the quantum and the material will appear as if reflecting the light quantum.
If the electron is not able to absorb the quantum because its energy state simply does not add up, then it will not be able to re-emit the quantum and so the material will appear as if it does not reflect the light quantum.
Red light on green colored object has no reflection and the object appears black.
What happen to the quantum not absorbed? It breaks up as it hit the nucleus, other electrons, etc. and dissipates.
So strictly speaking, the following account is wrong.
"For example, a red shirt looks red because the dye molecules in the fabric have absorbed the wavelengths of light from the violet/blue end of the spectrum. Red light is the only light that is reflected from the shirt. If only blue light is shone onto a red shirt, the shirt would appear black, because the blue would be absorbed and there would be no red light to be reflected."
Reflection is re-emission after absorption; the electron absorb the light quantum, transit down the band gap and when it returns from lower orbit it emit that quantum, and we see that as reflection. Other colored quanta are not absorbed and so not re-emitted (reflected). They simply dissipate in the lattice of the material. In order to be reflected the quantum must first be absorbed.
Have a nice day. Any one has a copper colored light?
