Ab initio calculations for the electronic states of (RbF)+ ionic excimer arising from the Rb+ +F, Rbzf + F-, Rb++F*, and Rb+F+ separated states are reported. The emission at 130 nm is shown to correspond to the transition between the ionic 2 'Z+ and 1 *C+ states which was estimated to occur at 124 nm with a spontaneous lifetime of 0.9 ns. The ionic 2 2rI state is found to lie close to the ionic 2 'I+ state and have a lifetime of 5.6 ns
The generation of coherent VUV and XUV radiation is presently one of the major objectives in quantum electronics. The rare gas halide excimers (RgX) are the most efficient media for lasers in the ultraviolet region [ I]. In order to extend the range for this type of lasers to even shorter wavelengths, ionic excimer molecules, which are isoelectronic in structure to the rare gas halides, have been proposed as possible VUV and XUV laser species [ 21, and other similar systems have also been discussed [ 3,4]. The production of such species by charged particle excitation and direct photoionization using the soft Xrays from a laser-produced plasma was first observed in CsF vapor [ 5,6], and the fluorescence was assigned to the 2C,,z-2Z,,r transitions between an inner-shell ionization state and an ionic ground state. Recently, emission spectra from CsF+ ( 185, I54 nm) RbF+ (130 nm) [B], KF+ (143 nm) [8], and XeRb+ (165 nm) [ lo], excited by charge transfer from rare gas ions and using a laser-produced plasma, have been observed.
In order to investigate whether the observed continue are the isoelectronic analogs to the rare gas halide transitions, the potential curves of the relevant states were calculated [8] using modified Rittner potentials [ 111. It was found that the lower state arising from the A+ + F separated ionic limit is unbound and the upper state is correlated with the