Three-Nucleon Transfer to Mirror States in ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{17}{}_{}{}^{}\mathrm{F}$

The highly selective reactions ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$(${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$)${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}({}_{}{}^{16}{}_{}{}^{}\mathrm{Li},t){}_{}{}^{17}{}_{}{}^{}\mathrm{F}$ have been used to populate mirror states below 7 MeV in ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{17}{}_{}{}^{}\mathrm{F}$. Negative-parity states are populated much more strongly than positive-parity states. The strongest state observed in ${}_{}{}^{17}{}_{}{}^{}\mathrm{F}$ is a new state at $E_x=5.220\mathrm{}\pm 0.01$ MeV, which is identified as the mirror of the 5.217-MeV state in ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$.