2+1+1 two-color REMPI study of the E1Π(ν=1)←D1Δ(ν=10)←X1Σ+(ν=0) transition in CO: influence of the accidental predissociation in the CO E1Π(ν=1) state at j=9 and 10

In the study of 2+1+1 two-color REMPI spectroscopy of the E1Π(ν=1)←D1Δ(ν=10)←X1Σ+(ν=0) transition in CO, the influence of the accidental predissociation in the E1Π(ν=1) state at j=9 and 10 was observed, which gives rise to the reduction of line intensity. It is consistent with Ubachsʹs model of spin–orbit-coupling between E1Π(ν=1) and k3Π(ν=6), which is itself predissociated by a 3Π repulsive state. Our experiment also confirmed Baker and Launayʹs calculation.