Elastic and inelastic scatterings of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$, and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ projectiles on ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ have been studied at corresponding bombarding energies to the scattering in regions of the vicinity of the strong absorption radius. Optical model and microscopic double-folding model analyses have been performed in order to define the nature of the optical potential depending on the projectiles. The analysis by the optical model calculations showed that the shallow potential ($V_R$=10 MeV) was not adequate for reproducing both the measured elastic and inelastic angular distributions, and a spin-dependent noncentral potential for the scattering systems ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$${,}^{14}$N${+}^{28}$Si was indispensable for obtaining the similar central potentials for all four projectiles. Analysis by the microscopic double-folding calculations supported the results of the optical model calculations.

• Received 8 February 1988

DOI:https://doi.org/10.1103/PhysRevC.37.2585