We have studied the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${}_{}{}^6{}_{}{}^{}\mathrm{Li}$,$t$) ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$)${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$, and ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$(${}_{}{}^7{}_{}{}^{}\mathrm{Li}$,$t$) ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ reactions at a laboratory angle of 15° and at incident energies of $E\left({}_{}{}^6{}_{}{}^{}\mathrm{Li}\right)=46\mathrm{}$ MeV and $E\left({}_{}{}^7{}_{}{}^{}\mathrm{Li}\right)=40\mathrm{}$ MeV. A selective population of final states leads to the identification of probable 3p-0h and 4p-1h configurations. Through the application of a folded-potential model to the ground-state band of ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$, we provide evidence for triton clustering outside a closed-shell core. In a comparison between (${}_{}{}^7{}_{}{}^{}\mathrm{Li}$,$t$) reactions leading to ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ and ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, the relationship between 4p-1h and 4p-0h configurations suggests that weak-coupling structure is involved.

NUCLEAR REACTIONS ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$(${}_{}{}^7{}_{}{}^{}\mathrm{Li}$,$t$), $E\left({}_{}{}^7{}_{}{}^{}\mathrm{Li}\right)=40\mathrm{}$ MeV, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${}_{}{}^6{}_{}{}^{}\mathrm{Li}$,$t$) and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$), $E\left({}_{}{}^6{}_{}{}^{}\mathrm{Li}\right)=46\mathrm{}$ MeV, ${\theta }_{\mathrm{lab}}=15\mathrm{}°$, measured ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ and ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ energy levels, calculated triton-cluster states.

• Received 7 June 1979

DOI:https://doi.org/10.1103/PhysRevC.20.1340