excitasjon
Excitasjon (excitation) is the process by which a system gains energy and moves from a lower-energy state to a higher-energy state. In atomic and molecular physics, excitation occurs when a particle absorbs energy—typically a photon or energy transferred in a collision—that promotes electrons to higher electronic, vibrational, or rotational levels. The excited state is usually unstable and relaxes back, often emitting radiation (fluorescence or phosphorescence) or transferring energy non-radiatively to the surroundings.
In spectroscopy, excitation refers to the absorption that induces transitions, producing excitation spectra that reveal energy-level
In solid-state physics, excitation can mean promotion of electrons across an energy gap, creating charge carriers.
In neuroscience, excitation describes the process by which a neuron becomes more likely to fire an action
Lifetimes of excited states vary from femtoseconds to milliseconds or longer, depending on the system and environment.