Absorption Spectrum: A plot of the wavelengths or frequencies of light that a substance absorbs, which can be used to identify the electronic transitions occurring in that substance.
Emission Spectrum:A plot of the wavelengths or frequencies of light that a substance emits, which can be used to identify the electronic transitions occurring in that substance as electrons return to lower energy levels.
Quantum Mechanics:The branch of physics that describes the behavior of matter and energy on the atomic and subatomic scale, including the principles that govern electronic transitions.