THEORETICAL-STUDIES OF VACUUM ULTRAVIOLET EMISSION-SPECTRA OF NELI+ AND ARLI+

Two of the ionic rare-gas alkali molecules, (Ne + Li) + and (Ar + Li)+, were studied with ab initio calculations. The first and second excited singlet states 2 1-SIGMA+ and 1 1-PI of both ions form excimers. The simulated emission spectrum from 2 1-SIGMA+ of NeLi+ peaks at 78.3 nm, and that form 1 1-PI peaks at 78.5 nm, while the recently observed experimental peak is 80.3 nm. The theoretical spectral profile is also in good agreement with the experimental one. The radiative lifetimes of the corresponding excited states (v' = 0) are 2.6 and 4.3 ns, respectively. For ArLi+, the theoretical spectrum from both excited states is 119.8 nm, while the experimental one is 124.7 nm. The lifetimes are 4.5 ns for 2 1-SIGMA+ and 23 ns for 1 1-PI.