Formation of CN(A 2Π i) fragment from BrCN in an argon flowing afterglow

Abstract

The vibrational bands of ν′ = 3–22 of the CN(A Π i−X 2Σ +) emission produced in the dissociative excitation of BrCN with Ar( 3P 0,2) were observed in the region 460–750 nm by a flowing-afterglow method under essentially collision-free conditions in order to investigate the formation dynamics of the CN(A 2Π i) fragment. The nascent vibrational distribution of the A 2Π i species was determined by a simulation analysis of the CN(A 2Π i−X 2Σ +) emission. A surprisal analysis of the vibrational distribution shows that the dominant mechanism producing the CN(A 2Π i) radical is energy transfer, being in parallel with that of the reaction producing the CN(B 2Σ +) radical.