Molecular states formed by ion beam neutralization of [C2H2]+ and [C2H3]+ on metal targets

Abstract

AbstractA combination of charge‐stripping and beam‐scattering techniques has been used to study the molecular states formed when a fast beam of [C2H2]+ and [C2H3]+ in several isotopic forms are neutralized by electron transfer from metal target atoms (K, Na, Mg and Zn). For [C2H3]+ the isotopic compositions and relative abundances of product states were found to be insensitive to the method of ion preparation (electron impact and chemical ionization). Ground state neutrals are formed in partial abundance when Mg or Zn is used as a target atom. With low ionization potential targets (K and Na) excitel dissociative states of C2H2 and C2H3 are formed as major beam constituents. For these states decomposition products have been identified and fragmentation energies measured. The excited states of C2H2 and C2H3 lie alout 6.8 eV and 2.9 eV, respectively, above their stable ground states. The discussion focuses on the possible identity of the excited states and their structural relations to the precursor ions.