ANALYSIS OF LOW-J PERTURBATIONS IN THE (B)OVER-TILDE(000)(2)SIGMA(U)(-STATE OF THE CO2+ MOLECULAR ION() ELECTRONIC)

The B(000)2SIGMA(u)+ state of the CO2+ molecular ion is known from pre vious work to be seriously perturbed at low J by two other vibronic st ates, as well as showing a number of other smaller perturbations at hi gher J. New spectra of ultraviolet emission bands with the B(000)2SIGM A(u)+ state as upper state, recorded with low rotational temperature t o emphasize the low-J transitions, are reported and analysed here. The se bands include the B(000)-X(000)2II(g) band and longer wavelength B( 000)-X(v1v2v3) bands observed in the region of the A(000)2II(u)-X(000) 2II(g) band. These long-wavelength bands are shown to be parallel band s with 2SIGMA(g)(+) or 2SIGMA(g)(-) lower states. It follows that the low-J perturbers of the B(000) state are one 2SIGMA(u)(+) and one 2SIG MA(u)(-) vibronic state. From their energies and symmetries, using the known parameters of the A2II(u) electronic state, these states can no w be identified as A(231) mu2SIGMA(u)(+) and A(151) k2SIGMA(u)(-). The parameters of the X 2II(g) electronic state permit the identification of the lower states of the long-wavelength bands as X(v1, 3, v3)mu2SI GMA(g)(+) or X(v1, 5, v3)k2SIGMA(g)(-) with v3 = 1 or 3 and with vario us values of v1. This analysis is shown to agree with various features of previously observed spectra. Fits of the relative intensities of t he rotational lines give rotational temperatures of 38 K and 35 K in t wo different jet-expansion sources, together with values of theta para meters where tan theta is the ratio of the A(151) k2SIGMA(u)(-)-X(v1 v 2 v3)2SIGMA(g) and A(231)mu2SIGMA(u)(+)-X(v1 v2 v3)2SIGMA(g) transitio n moments. These new data can be used to improve the empirical potenti als of the X and A electronic states, and the relative intensities sho uld give information on the Franck-Condon overlaps of their vibronic w avefunctions.