Single-Particle Effects on Fission Probabilities for the Lighter Elements

The excitation energy dependence of the competition between neutron emission and fission has been calculated for nuclei in the vicinity of the ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ closed shell. A two-center model has been used to calculate single-particle effects on the nuclear level density as well as on the barrier heights. Comparison with experiment demonstrates the importance of including the dependence of the single-particle level density on deformation.