Two thermodynamically stable states in SiO- and PN-

In contrast to the well-known CO and N-2 molecules, isoelectronic SiO and P N form thermodynamically stable conventional (valence) and dipole-bound ani on states upon attachment of an extra electron. According to the results of our high-quality nb initio calculations, binding energies of the electron in these states art: 38 and 1.6 meV (SiO-) and 76 and 1.0 meV (PN-), respec tively. Dissociation trends of the SiO- and PN- anions are discussed. [S105 0-2947(98)01312-2].