Disappearance of theN=14shell

An excited state of ${}^{22}\mathrm{N}$ unbound with respect to neutron emission was observed in a stripping reaction from a 85 MeV/nucleon ${}^{26}\mathrm{F}$ beam. The observed decay energy of 650(50) keV places the level, which is interpreted to be the first $3^{-}$ state, at an excitation energy of 1.93(22) MeV. Together with the previously measured bound states of ${}^{22}\mathrm{N}$, reduction of the $N=14$ shell gap compared to less neutron-rich nitrogen isotopes at the neutron dripline is observed. Based on the magnitude of the reduction of the shell gap for ${}^{22}\mathrm{N}$, a disappearance of the gap and even a level inversion of the $\nu 1s_{1/2}$ and the $\nu 0d_{5/2}$ levels in the neutron-unbound nucleus ${}^{21}\mathrm{C}$ seems likely.