Analytic representation of the ground state potential surfaces for CO−2 and CO2. Implications for the O− + CO → CO*2 + e chemiluminescent reaction and other related processes

Abstract

A reasonable approach to the establishment of full-range analytic potential energy hypersurfaces for CO−2 X2A1(12IIu. 12A′) and CO2 X1Σ+g(11A1, 11A′) has been demonstrated. The functional representations employed are based on the use of ab initio calculations for selected regions. This result will facilitate detailed dynamics computations for state-to-state energy disposition in the O−(2P) + CO(X1Σ+, v) → CO2(X1Σ+g, v′1, v′2, v′3) + e chemiluminescent reaction. The locus of the intersection of the ground state potential energy surfaces for CO−2 and CO2 has been located with these full-range analytic representations. The minimum in this locus is found to be V* = 0.78 eV, R*CO = 1.23 A and AOCO = 152°, where V* is measured relative to the potential minimum for vibrationless CO2(X1Σ+g). This critical point is 0.44 eV above the potential minimum for vibrationless CO−2(X2A1), which is presently located at ReCO = 1.256 A, AeOCO = 135.5°. The implications of these results for the stability of CO−2 and for the reactions O− + CO, CO−2 + M → M + CO2 + e and other processes are discussed.