LINEAR ALUMINUM-DOPED AND PHOSPHORUS-DOPED CARBON CLUSTER ANIONS - MASS-DISTRIBUTION AND AB-INITIO CALCULATIONS

Both aluminum- and phosphorus-doped carbon cluster anions were produce d by laser ablation on mixed powder samples. Dramatic even/odd alterna tion of the cluster ion signal intensity can be observed in their reco rded mass spectra. The mass distributions reveal that the CnAl- cluste rs with even n are more stable than those with odd n, while the CnP- c lusters with odd n are more stable than those with even n. The contrar y parity effects are confirmed by ab initio Hartree-Fock calculations carried out on a linear cluster model. Calculated energies, which are expressed as the energy difference between the adjacent clusters as we ll as the binding energy and the electron binding ene-gy, and optimize d geometries of the clusters also favor the singlet species, which are the CnAl- clusters with even n and the CnP- clusters with odd n. (C) 1998 Elsevier Science B.V.