A density-functional study on the formation of Mo2+2

Abstract

The presence of metastable states in the doubly ionized molybdenum dimer is studied using gradient-corrected scalar-relativistic density-functional theory. Seventeen metastable states are found within an energy range of less than 6.5 eV. All those states show lifetimes large enough to assure experimental detection. The calculation of the second adiabatic ionization potential of the neutral molybdenum dimer seems to confirm that the doubly ionized dimer is produced by the electron-capture process Mo2+ + Ar+ → Mo2 2+ +Ar, in which the ionization potentials of Ar and Mo2+ play a crucial role [K. Franzreb, R. C. Sobers, Jr., J. Löriņik, and P. Williams, J. Chem. Phys. 120, 7983 (2004)]. Moreover, the present results indicate that other species having ionization potentials between 13.01 and 15.34 eV could be used as projectiles to produce Mo2 2+. It is also shown that Xe+ ions could not react with Mo2+ to produce double ionized dimers. A simple thermodynamic argument is also proposed that seems to increase the possibilities of forming Mo2 2+ from Mo2+ by using Ar+ as projectile ions.