EXPERIMENTAL AND THEORETICAL WORK OF DOUBLY CHARGED MOLECULAR IONS: $N^{2+}_{2}$ AND $CO^{2+}$

Abstract

$^{1}$ B.J. Olsson, G. Kindvall and M. Larsson, J. Chem. Phys. (in press).Author Institution: Research Institute of Physics, Frescativagen 24Only a few doubly charged molecular ions are known to possess emission spectra. The $^{1}\Sigma^{+}_{u}-x^{1}\Sigma^{+}_{g}$ transition of $N^{2+}_{2}$ was rotationally analyzed by Carroll already 1958 and more recently by Cossart and coworkers. We have used the high frequency deflection technique to perform the first direct vibrationally resolved measurement of a fluorescence lifetime of a doubly charged molecular $ion^{1}$. Furthermore, we have used the complete active space SCF (CASSCF) method to calculate the electronic transition moment function of the D-X transition. The contracted CI (CCI) method was used to improve the potential curves obtained at the CASSCF level and the radiative lifetime was obtained with help of these potential curves and the electronic transition moment function. The experimental and theoretical lifetimes, 6.010.5 and 8.0 ns respectively, are in good agrecement. No emission from the $CO^{2+}$ ion has yet been observed. The CASSCF and CCI methods have been used to obtain potential curves of low lying triplet states of $CO^{2+}$.With these curves as guidance, emission from $CO^{2+}$ following electron impact on jet cooled CO have been searched for. We also plan to search for a laser induced predissociation spectnm of $CO^{2+}$ with the fast ion beam laser technique