An excited state isn't a barrier, it's a state with a higher energy than ground state. Several non-ground-state orbitals have a wavefunction whose amplitude dro

An excited state isn't a barrier, it's a state with a higher energy than ground state. Several non-ground-state orbitals have a wavefunction whose amplitude drops to zero toward the centre. An electron won't tunnel to a location where its wavefunction amplitude is zero.