Absorption of pions minus by Bi, Pb, Tl nuclei

The Bi+π-, Pb+π- and Tl+π- reactions are investigated. Apart from neutron emission the escape of charged particles is considered. Data on the yields of different isotopes and excitation of high-spin isomers are discussed within the framework of the cluster representation of nuclear structure. Identification of the sup(200m)Au, sup(198m)Au, sup(196m)Au high-spin isomers among the products of the Tl+π- reaction shows most clearly, that the excitation of high-spin nuclear states in the pion absorption is observed both in the Z-1 nuclei and in the Z-2 where Z is atomic number. Detected is prevailing enrichment of heavy nucleus surface with the np clusters in comparison with the pp clusters. The ratio of the np- to the pp clusters on the nucleus surface is 5.0+-2.8