THERMAL-ENERGY CHARGE-TRANSFER, QUENCHING, AND ASSOCIATION REACTIONS OF DOUBLY CHARGED IONS IN THE RARE-GASES

A drift-tube mass-spectrometer apparatus has been used to determine thermal-energy (300 K) charge transfer rate coefficients for reactions of the type Ra2++RbRa++Rb+* and Ra2++RbRa++Rb2++e- (transfer ionization), where R=He,Ne,Ar,Kr,andXe. Rate coefficients for ions in the low-lying, metastable excited states (S1 and D1) as well as the ground state (P3) have been determined and, in some cases, deexcitation (quenching) coefficients for S1 and D1 ions have been measured. Reactions with an exoergicity E4 eV are found to be fast, approaching the limiting Langevin rate, while for E<2 and >7 eV the rates fall off dramatically, in some cases dropping to the radiative value (10-14 cm3/sec). The equilibrium constant for the three-body association reaction Xe2+ + 2 Ne(Xe Ne) 2+ + Ne has been determined at 300 K. © 1979 The American Physical Society.