I believe I have a misunderstanding of some principles, but I have not, even through quite a bit of research, been able to understand this problem.
My current understanding of transmission, reflection and absorption is as follows:
transmission occurs when the energy of an incident photon does not correspond to any electron's energy transition within the material. Therefore, the photon does not interact with the atoms / electrons and is transmitted through.
Absorption occurs when the incident photon's energy exactly equals that of an electron's energy transition. The photon is absorbed and excites an electron to a higher state.
Reflection I feel like my understanding is flawed, since I have read multiple different views. I believe that a photon is absorbed by an atom, exciting an electron. The electron, however, almost immediately transitions back into a lower energy level, emitting a photon of identical wavelength.
My question concerning reflection is:
- Why are some wavelengths absorbed and immediately re-emitted? I presume that it is because the electron is in a type of unstable state and therefore drops back to its previous energy level?
Given a solid object that appears red to us (therefore reflects wavelengths somewhere between 625 and 740nm), how can it be possible that all other incident wavelengths are absorbed? They must be absorbed, since the only wavelength being reflected is in the "red" range, and I can clearly see there's no visible light being transmitted through the object. However, in my knowledge, the wavelengths can only be absorbed if they correspond to the energy transition of an electron, which is not the case for every wavelength in the visible spectrum.
How is it then possible that they are absorbed? Additionally, if the electron is excited to a higher level, does it just store the energy? Does it take thermal form??
I assume that perhaps I cannot simply apply these principles of absorption, that I was taught only in relation to a single atom, to a complex body consisting of billions of atoms. Could someone elaborate on this and explain my questions about absorption and reflection? Thanks very much!