Multistep transfer of nucleons and the formation of molecular orbitals

The question of multistep transfer is studied in the framework of coupled reactions channel analysis. Neutron transfer and direct excitation of single particle states in the system 12C + 13C are calculated in a coupled channel formalism. Angular distributions and excitation functions for excited states are discussed. It is found that the coupling between ground states and excited states is weaker than the coupling between excited states. Inelastic excitation tends to increase the transfer coupling via polarisation (hybridization effect) of the orbitals. Thus in states of the total system with positive parity the coupling between ground and excited states is strong, while it is weak in negative parity states. The formation of molecular orbitals of the neutron in the 12C + 13C system is illustrated and their significance for the understanding of the different reaction channels are discussed. (author)