Long description

Three atoms are illustrated on the page, each with a central nucleus (brown circle) surrounded by two rings. From left to right: in the ground state, an electron (blue circle) is present on the inner ring. If energy from light (indicated by the blue wavy line with an arrowhead in the middle image) is absorbed by the electron, it moves to the outer ring. From there, the electron returns to the ground state on the inner ring again (right hand side). During this process it emits fluorescent light (indicated by the red wavy line with an arrowhead).