Rotational perturbations in the CN(<i>B</i>²Σ⁺–<i>X</i>²Σ⁺) tail band system. III. Molecular constants for the ⁴Π, ⁴Σ⁺, <i>A</i>²Π_<i>i</i>, and <i>X</i>²Σ⁺ states

<jats:p> The CN(B<jats:sup>2</jats:sup>Σ<jats:sup>+</jats:sup>–X<jats:sup>2</jats:sup>Σ<jats:sup>+</jats:sup>) tail band system was observed by using the dissociative excitation reactions of HCN and BrCN with Ar(<jats:sup>3</jats:sup>P<jats:sub>0.2</jats:sub>) in an argon flowing afterglow. The following intensity anomalies owing to the B<jats:sup>2</jats:sup>Σ<jats:sup>+</jats:sup> ~ <jats:sup>4</jats:sup>Π rotational perturbations were analyzed: (ν<jats:sub>B</jats:sub>, ν<jats:sub>11</jats:sub>) = (9,x), (11,x + 2), and (18,x + 13), where x is estimated to be 0 or 1. These anomalies, as well as(ν<jats:sub>B</jats:sub>, ν<jats:sub>11</jats:sub>) = (12,x + 3), (14,x + 6), and (17,x + 11), were analyzed by spectral simulation. The CN(B<jats:sup>2</jats:sup>Σ<jats:sup>+</jats:sup>–X<jats:sup>2</jats:sup>Σ<jats:sup>+</jats:sup>) 14–14 band spectrum observed by Jenkins was re-analyzed, and the molecular constants for the perturbing <jats:sup>4</jats:sup>Π state, the interaction constants, and the crossing schemes for the B<jats:sup>2</jats:sup>Σ<jats:sup>+</jats:sup> ~ <jats:sup>4</jats:sup>Π perturbations were determined. The intensity anomalies due to the perturbations by the <jats:sup>4</jats:sup>Σ<jats:sup>+</jats:sup>, A<jats:sup>2</jats:sup>Π<jats:sub>i</jats:sub>, and X<jats:sup>2</jats:sup>Σ<jats:sup>+</jats:sup> states were also observed: (ν<jats:sub>B</jats:sub>, ν<jats:sub>Σ</jats:sub>) = (15,p + 6), where p is estimated to be 8 ± 1, (ν<jats:sub>B</jats:sub>, ν<jats:sub>A</jats:sub>) = (11, 26) and (17, 34), and (ν<jats:sub>B</jats:sub>, ν<jats:sub>X</jats:sub>) = (11, 28). The molecular constants for the perturbing levels were estimated by a simulation analysis. </jats:p>