Radiative transition probabilities in the X2Πg state of CO+2

Using ab initio calculated potential energy and electric dipole moment functions, absolute radiative transition probabilities between the rovibronic Renner-Teller states of the electronic ground state X 2 Πg ofCO+2 have been evaluated. The rovibronic eigenstates were obtained (up to 6500 cm -1 and J≤13 2 from variational calculations including the Renner-Teller and spin-orbit angular momentum couplings. The absolute intensities for the rovibrational states of the neutral CO 2 electronic ground state, calculated by a similar approach, are found to be in excellent agreement with experimental data. For CO+2 the presented results are expected to have similar accuracy. It is found that the overtone intensities of the antisymmetric stretching mode of CO+2 are of similar magnitude as the fundamental transitions, in contrast with CO 2 . The theoretically generated IR-emission spectrum is compared with the limb spectrum of the Mars atmosphere, measured by the Thermal Emission Spectrometer on Mars Global Surveyor.