We perform second-order distorted-wave Born-approximation analyses of the ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}(p, t){}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ $2^{-}$ excitation. The experimental angular distribution can be well reproduced by the simultaneous consideration of ($p, t, t^{\prime }$), ($p, p^{\prime }, t$), and ($p, d, t$) processes and the last two processes are found to be comparably important. The phase relations in the nonorthogonal term are also discussed and it is shown that this term gives a negligibly small contribution to such unnatural-parity-state excitation processes.

• Received 22 April 1975

DOI:https://doi.org/10.1103/PhysRevLett.35.357