Absorption spectra baffle me and I've never seen an explanation that helps me understand.
It seems conceptually simple, except the requirement that the energy of an photon exactly match some required energy in order to be absorbed seems really unlikely, since photon energy not a discrete quantity, and varies according to doppler effects and other things.
It seems like the vast majority of photons would just fly through the universe without interacting with anything, unless there are other ways for photons to interact with matter besides being absorbed. (If there are other ways, they are seemingly never mentioned as a potential alternative fate for the photon).
> It seems like the vast majority of photons would just fly through the universe without interacting with anything, unless there are other ways for photons to interact with matter besides being absorbed.
Maybe someone who actually knows will chime in, but afaik:
- Most light doesn't have a fixed frequency. If it did, it would have a fixed momentum, but then you would have no idea where it is! Instead it is some superposition of many frequencies. That could be part of the story.
- Light could be stopped by something other than absorption into an individual atom. Metals don't have discrete spectra.
The match between the energy of the photon and the atom orbits doesn't have to be perfect. Part of the energy may be added or removed as vibrations (phonons).
It seems conceptually simple, except the requirement that the energy of an photon exactly match some required energy in order to be absorbed seems really unlikely, since photon energy not a discrete quantity, and varies according to doppler effects and other things.
It seems like the vast majority of photons would just fly through the universe without interacting with anything, unless there are other ways for photons to interact with matter besides being absorbed. (If there are other ways, they are seemingly never mentioned as a potential alternative fate for the photon).