Well, the simple fact, that light is emmitted does not necessarily imply, that the signature must be unique or very specific to any molecule. That is something

Well, the simple fact, that light is emmitted does not necessarily imply, that the signature must be unique or very specific to any molecule. That is something with probably a way more complicated explanation, if one wants to dig deeper. I suspect something something quantum will also play a role, so probably without studying physics not properly understandable in depth.