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

The kinetics of depletion of the lowest two electronically excited states, Co(b F-4(J)) and Co(a(2)F(J)), upon interactions with O-2 and N-2 are studied in a fast-flow reactor at a He pressure of 0.70 Torr. The depletion of Co(b F-4) or Co(a F-2) by O-2 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 O-2. Efficient depletion upon interaction with O-2 was interpreted through the occurrence of an intermediate formed by the interaction between singly occupied anti-bonding pi* orbital of O-2 and 3d orbitals of Co.