electronic activation

In physics, excitation is the process of adding a discrete amount of energy to a system, such as an atom or molecule, causing it to move from its lowest energy state (ground state) to a higher energy state (excited state). This added energy is called excitation energy.1

Excited states have specific, discrete energy values, meaning energy can only be absorbed in corresponding discrete amounts. For example, exciting a hydrogen atom requires 10.2 electron volts to move an electron to its first excited state.1

When atoms or nuclei return to their ground states, they release this stored energy, often as visible light from atoms or gamma radiation from nuclei. This process is a primary way matter absorbs electromagnetic energy and can be heated or ionized. Molecules can also be electronically activated, leading to unusual chemical reactions or light emission, known as luminescence.12