Formation and stability of antimony and bismuth oxide clusters: a mass spectrometric investigation

Antimony oxide and bismuth oxide clusters are produced in a gas aggregation source. The pure metal (Sb, Bi) mixed with molecular oxygen as the reaction gas or alternatively the solid metal oxide (Sb2O3, Bi2O3) is vaporised into a Row of cold helium carrier gas. The resulting products are photoionised with a KrF short-pulse excimer laser and detected in a combined Wiley-McLaren/reflectron time-of-flight mass spectrometer. Independently of the used educts, oxides following the general sequence MO(M2O3)(n)(+) (where M is Sb or Bi) become most abundant. The stability of these hitherto unknown cluster ions is explained in terms of minimising the number of the unpaired electrons by the building of metal-oxygen electron pair bonds. (C) 1997 Elsevier Science B.V.