The heavy residues emitted following the interaction of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ have been measured for ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ bombarding energies from 12 to 35 MeV. The gross characteristics of the residue spectra are in qualitative agreement with a fusion-evaporation mechanism. Beginning at Coulomb barrier energies, it is found that the total fusion cross section diverges from the total reaction cross section obtained from optical model fits to ${}_{}{}^6{}_{}{}^{}$Li${+\mathrm{}}^{16}$O elastic scattering data. The importance of the process which limits the ${}_{}{}^6{}_{}{}^{}$Li${+\mathrm{}}^{16}$O fusion cross section is attested to by the fact that only 60% of the total reaction strength can be accounted for by fusion at our highest bombarding energies. A comparison of the total fusion cross sections as a function of center-of-mass energy for the ${}_{}{}^6{}_{}{}^{}$Li${+\mathrm{}}^{16}$O and ${}_{}{}^7{}_{}{}^{}$Li${+\mathrm{}}^{16}$O entrance channels reveals essentially identical total fusion cross section excitation functions. This result contrasts sharply with the results obtained in an earlier study of ${}_{}{}^6{}_{}{}^{}$,7Li-induced reactions on ${}_{}{}^{12}{}_{}{}^{}$,13C nuclei. In the earlier study, fusion cross sections which were projectile dependent and target independent were observed. Finally, the critical angular momenta have been extracted from the ${}_{}{}^6{}_{}{}^{}$Li${+\mathrm{}}^{16}$O total fusion cross sections. When compared with the critical angular momenta obtained from an earlier study of the ${}_{}{}^{10}{}_{}{}^{}$B${+\mathrm{}}^{12}$C entrance channel, a common limitation is found with increasing ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ excitation energy. This result is in sharp contrast with the result of an earlier study of entrance channels which form the ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$ compound nucleus, a compound system only one neutron removed from ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$.

• Received 21 January 1986

DOI:https://doi.org/10.1103/PhysRevC.33.1649