Kinetics of depletion of Co(b 4F) and Co(a 2F) atoms by O2

The kinetics of depletion of the lowest two electronically excited states, Co(b 4FJ) and Co(a 2FJ), upon interactions with O2 and N2 are studied in a fast-flow reactor at a He pressure of 0.70 Torr. The depletion of Co(b 4F) or Co(a 2F) by O2 was efficient. The depletion rate constants were observed to be different among spin-orbit levels within one electronic state. Because reactive channels are not energetically accessible for these two states, the depletion was mostly attributed to electronic energy transfer to vibration or translation of O2. Efficient depletion upon interaction with O2 was interpreted through the occurrence of an intermediate formed by the interaction between singly occupied anti-bonding π∗ orbital of O2 and 3d orbitals of Co.