Three gas-phase diatomic trications Se 2 3+, Te 2 3+, and LaF 3+ have been produced by Ar + ion beam sputtering of Se, Te, and LaF 3 surfaces, respectively. These exotic molecular ions were detected at noninteger m/z values in a magnetic sector mass spectrometer for ion flight times of ≥13 μs that correspond to lower limits of their respective lifetimes. Se 2 3+ and Te 2 3+ were unambiguously identified by their characteristic isotopic abundances. Ab initio calculations of the electronic structures of Se 2 3+, Te 2 3+, and LaF 3+ show that these molecular trications are metastable with respect to dissociation into fragment ions of Se 2++Se +, Te 2++Te +, and La 2++F +, respectively. Their barrier heights are about 0.49, 0.29, and 0.53 eV, and the equilibrium internuclear distances (bond lengths) are about 0.23, 0.27, and 0.26 nm, respectively. The gas-phase diatomic dications Se 2 2+ and Te 2 2+ were also observed and unambiguously identified. They were found to be long-lived metastable molecules as well, whereas LaF 2+ is thermochemically stable.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry