Identification of the SiF₆²⁻ dianion by accelerator mass spectrometry and a fully relativistic computation of its photodetachment spectrum

Author(s)

Hubert Gnaser, Robin Golser, Markus Pernpointner, Oliver Forstner, Walter Kutschera, Alfred Priller, Peter Steier, Anton Wallner

Abstract

The small doubly-charged molecular anion SiF62− was studied by two distinct approaches, one experimental the other theoretical. The dianion was produced in the gas phase by sputtering a Li2SiF6 specimen with Cs+ ions and was detected by means of accelerator mass spectrometry. The identification was via the Si29F62−19 isotopomer; it has an odd total mass and therefore the dianion shows up at a half-integral mass-to-charge ratio (M∕q=71.5amu) in the mass spectrum, facilitating a positive identification. The flight time through the mass spectrometer of ≈10μs establishes a lower limit with respect to the intrinsic lifetime of this species. Attempts to detect the SiF62− dianion also by secondary-ion mass spectrometry failed, but provided an upper limit in terms of its formation probability with respect to the F− ion of Si29F62−19/F−19<2×10−9. Furthermore, theoretical calculations of the photoelectron spectrum by means of the relativistic one-particle propagator predict considerable stability of the dianion against autodetachment. The first ionization potential of SiF62− was determined as 2.79eV at the optimized bond length of 1.718Å in the gas phase.

Organisation(s)

Isotope Physics

External organisation(s)

Technische Universität Kaiserslautern, Scientific Software Center

Journal

Physical Review A

Volume

77

No. of pages

7

ISSN

1050-2947

DOI

https://doi.org/10.1103/PhysRevA.77.053203

Publication date

2008

Peer reviewed

Yes

Austrian Fields of Science 2012

103005 Atomic physics

Portal url

https://ucrisportal.univie.ac.at/en/publications/b858a8e3-1fe0-49f2-8f9a-30ea7988d107