Tricationic metastability by symmetry restrictions: B2n+, n = 3,4
IFISR – International Foundation for Independent Scientific Research, 576 Fifth Ave, Suite 903, New York, NY 10036, USA
Received: 5 August 2016
Received in final form: 22 October 2016
Published online: 10 January 2017
To explain the experimentally observed metastability of the trication B23+, we study this system by various ab-initio methods. Whereas the electronic ground state X2Σu+ of B23+ turns out to be unstable, the potential energy curves of the lowest excited state 12Πu and of the quartet state 14Σg− form barriers that support quasi-bound vibronic states. The lifetimes of these states are not only determined by the respective (dissociative) tunnelling rates, but also by possible radiative electronic transitions and predissociation via spin-orbit coupling, where the latter furnish the decisive decay mechanism for the low-lying vibronic levels. In case of the quadruply charged system B24+, our computations do not predict any metastable states in the low-lying electronic spectrum. The deviation from a purely Coulombic repulsive behaviour in B24+ is quantified by fitting the potential energy curves to a modified Murrell-Sorbie function.
Key words: Molecular Physics and Chemical Physics
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2017