Definition of Excited State
Excited-state is such a state of a system that has energy higher than the ground state. Excitation is a promotion in energy level that is above a baseline energy state. The temperature of the group of particles or atoms gives us information about the level of excitation.
The period of excitation state is relatively very short. When an atom is excited, it usually emits a photon spontaneously and in this way, it returns to its normal ground state. This returning of an atom to its ground state is often described as decay and it is the opposite of excitation.