The GSI/FAIR facility has been used to produce at a relativistic kinetic energy of 540 MeV/u a beam of neutron-rich light isotopes in the region of nitrogen. In particular, the projectiles of 19N
impinging on a liquid hydrogen target can be used to populate unbound states of neutron-rich carbon isotopes, such as 18C. The decaying 18C∗ →17C+n system is studied by detecting in coincidence the evaporated neutron and the fragment, as well as the emitted 𝛾-rays. The invariant mass method in inverse kinematics is employed to reconstruct the energy spectrum of the fragment above its neutron separation energy, finding in this work a clear third resonance-like structure with a higher strength than the previously reported ones.