De-excitation

Contents

Key Stage 5

Meaning

De-excitation is the process in which an atom loses energy by photon emission as a result of an electron moving from one energy level to an unoccupied position in a lower energy level.

About De-excitation

• De-excitation occurs when an electron in a higher energy level falls to a lower energy level.
• The energy difference between the two levels is emitted as a photon.
• The emitted photon has an energy exactly equal to the energy difference between the levels.
• De-excitation is the reverse of excitation, where energy is absorbed to move an electron to a higher level.
• Important in the study of atomic spectra and the identification of elements.

Examples

• The emission of light in neon signs is due to the de-excitation of electrons in neon atoms.
• De-excitation of electrons in hydrogen atoms produces the characteristic lines of the hydrogen spectrum.