title: Gas-phase diatomic trications of Se2(3+), Te2(3+), and LaF3+.
abstract: 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 micros 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.
authors.affiliation: Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, USA.
authors.forename: K
authors.initials: K
authors.lastname: Franzreb
authors.forename: J
authors.initials: J
authors.lastname: Hrusák
authors.forename: M E
authors.initials: ME
authors.lastname: Alikhani
authors.forename: J
authors.initials: J
authors.lastname: Lörincík
authors.forename: R C
authors.initials: RC
authors.lastname: Sobers
authors.forename: P
authors.initials: P
authors.lastname: Williams