Excitation energy

In physics, excitation energy is understood to be the energetic distance between an excited state and its basic state in a physical system with discrete or continuous excitation states . For example in an atomic electron system , molecule , atomic nucleus , potential field or solid - electron or phonon system.

In a quantum mechanical "small" many-particle system such as B. the electron shell of an atom or the building blocks of the atomic nucleus, only a few specific, discrete energy levels are possible - which also requires a limited number of possible energy jumps when transitioning between two levels. And even in the quasi-continuous states of "large" systems with energy bands there is a state of minimal energy, or quasi-separable degrees of freedom of excitation with states of minimal energy.

The state with the lowest energy is called the ground state. All other states have a higher energy than this, namely the excitation energy . Usually the energy of the ground state is arbitrarily set equal to zero, so that the excitation energies are the energies related to the ground state.