A tentative explanation of the broad plateau observed in the spectra of directly scattered helium ions producing highly excited nuclear states is advanced. In the case of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ projectiles, we propose that, in addition to the suggested formation of short-lived ${}_{}{}^5{}_{}{}^{}\mathrm{He}$ (${}_{}{}^5{}_{}{}^{}\mathrm{Li}$), the excitation of single-particle states in the continuum with and without subsequent nucleon emission can account for the data. Calculations are presented which corroborate this conjecture.

• Received 15 September 1971

DOI:https://doi.org/10.1103/PhysRevLett.27.1657