What happens to an atom when it absorbs energy and enters an excited state?

When an atom absorbs a discrete amount of energy, such as a photon, its electrons undergo a "quantum leap" from a lower energy level to a higher, allowed orbit. This transition places the atom into an excited state, which is a condition of higher energy than its ground state.123

Because excited states are generally unstable, the atom typically remains in this condition for only a very short time—often on the order of ${10}^{-9}$ to ${10}^{-8}$ seconds—before returning to a lower energy state. During this return, the atom releases the stored energy, usually by emitting a photon. In the context of laser technology, this process can be controlled through stimulated emission, where an incoming wave forces excited atoms to release their energy in a way that produces coherent, monochromatic light. Alternatively, this energy can be lost through collisions with other particles.4125