2-CENTER MOLECULAR-STATES IN B-9, BE-9, BE-10, AND B-10

The molecular states in the mass 9 and 10 nuclei, which consist of two alpha-particles plus one or two valence nucleons (protons or neutrons ) are discussed. Arguments for the existence of two-center dimers as e xcited states in Be-10 and corresponding resonances (p + Be-9) in B-10 are given. The latter states are observed as anomalous (non statistic al) population in the final state interactions in the p + Be-9 channel in various heavy ion collisions. With the establishment of two-center states (dimers) based on the alpha alpha-potential and a localized bi nding via two nucleons in Be-10, the existence of more extended struct ures (multimers) by adding (alpha 2n) structures to Be-10 is postulat ed. Generally clustering into alpha-particles and nucleons in terms of molecular states is expected to occur at excitation energies close to the threshold for these substructures in analogy to the clustering ru les of Ikeda for alpha-particle nuclei. Consequences to clustering pro perties of neutron rich nuclei are discussed.