MASS SPECTROMETRIC DETECTION OF ALKALINE EARTH MONOHALIDE DICATIONS

Quadrupole mass spectrometry has been used to detect BaX2+ (X = F, Cl, Br, I), SrCl2+, CaBr2+, and MgBr2+. Dications were produced by electron bombardment of an effusive beam containing the stable alkaline earth monohalide radical precursor. All species but MgBr2+ are predicted to be thermodynamically stable. MgBr2+ is likely to be metastable but with a lifetime sufficiently long to allow its detection in the millisecond timescale. Simple arguments are presented for the expected trends in stability.