What are meant by excitation potential and ionisation potential ?

Explanation

The excitation potential is the potential to be applied to an electron in the outermost shell of an atom to lift it to an excited energy state . On the other hand, the ionisation potential is the minimum potential to be applied on that electron to bring it outside the atom so that the atom is ionised. For example, the excitation potential of the ground state electron of a hydrongen atom is 10.2 V for transition of the first excited state . where as the ionisation potential of that electron is 13.6 V .