Radiative lifetimes of A 2Π, B 2Σ+, a 4Σ+, and b 4Δ states of CP radical

•B2Σ+1/2 – X2Σ+1/2 transition is strong.•A2Π1/2, 3/2 – X2Σ+1/2 and B2Σ+1/2 – A2Π1/2, 3/2 transitions are strong.•Lifetimes are 10 μs for the A2Π1/2, 3/2 states and 100 ns for the B2Σ+1/2 state.•Lifetimes are 10 and 10 – 100 ms for the a4Σ+1/2 and a4Σ+3/2, respectively.•Lifetimes are 10, 0.1 – 1, and 10 ms for the b4Δ1/2, b4Δ3/2, and b4Δ5/2 states, respectively. The potential energy curves of X 2Σ+, A 2Π, B 2Σ+, a 4Σ+, and b 4Δ states and their Ω states of CP were calculated using the icMRCI approach. The transition dipole moments between these states were computed. To improve the accuracy of the potential energy curves, core–valence correlation and scalar relativistic corrections were considered. The radiative lifetimes were approximately 10 μs for the A 2Π3/2 and A 2Π1/2 states and 100 ns for the B2Σ+1/2 state; those were approximately 10, 10 – 100, 10, 0.1 – 1, and 10 ms for the a 4Σ+1/2, a 4Σ+3/2, b 4Δ1/2, b 4Δ3/2, and b 4Δ5/2 states, respectively. The spontaneous emissions from the B 2Σ+1/2 – X 2Σ+1/2 system were strong, followed by the A 2Π3/2 – X 2Σ+1/2, A 2Π1/2 – X 2Σ+1/2, B 2Σ+1/2 – A 2Π3/2, and B 2Σ+1/2 – A 2Π1/2 transitions. The strong emissions from the A 2Π3/2 – X 2Σ+1/2 and A 2Π1/2 – X 2Σ+1/2 systems were in the infrared region; those from the B 2Σ+1/2 – X 2Σ+1/2 system were in the visible and ultraviolet regions; and those from the B 2Σ+1/2 – A 2Π3/2, and B 2Σ+1/2 – A 2Π1/2 systems were of visible light. A simple comparison shows that the effect of the spin–orbit coupling on the radiative lifetimes of the A 2Π and B 2Σ+ states was significant. The radiative–lifetime distribution of each level υ versus the rotational quantum number J was evaluated for υ ≤ 15 and J ≤ 70.5. The PECs of the X2Σ+, A2Π, B2Σ+, a4Σ+, and b4Δ states and their Ω states of CP are calculated. The TDMs between these states are computed. The radiative lifetimes are of the order of 10 μs for the A2Π3/2 and A2Π1/2 states and 100 ns for the B2Σ+1/2 state. Those are of the order of 10, 10 – 100, 10, 0.1 – 1, and 10 ms for the a4Σ+1/2, a4Σ+3/2, b4Δ1/2, b4Δ3/2, and b4Δ5/2 states, respectively. The SOC effect evidently increases the radiative lifetime of the A2Π state; however, it significantly decreases the radiative lifetime of the B2Σ+ state. The B2Σ+1/2 – X2Σ+1/2 transition is strong, followed by the A2Π3/2 – X2Σ+1/2, A2Π1/2 – X2Σ+1/2, B2Σ+1/2 – A2Π3/2, and B2Σ+1/2 – A2Π1/2 transitions. The strong emissions from the A2Π3/2 – X2Σ+1/2 and A2Π1/2 – X2Σ+1/2 systems are in the IR