Energy transfer processes in CH A^2Δ and B^2Σ^− in an atmospheric pressure flame

Laser-induced fluorescence studies have been made of the CH radical in atmospheric pressure flames of methane, oxygen, and nitrogen. Individual rotational levels within the υ′ = 0 and 1 vibrational levels of the A2Δ and B2Σ− states are excited by a dye laser operating in the 380–440-nm region. Studies were made of collisional energy transfer pathways within and between the states, using rotationally resolved fluorescence scans. Rotational transfer occurred at a rate, dependent on rotational level, 2–5 times that of quenching. Vibrational transfer was slow but transfer between A(υ′ = 1) and B(υ′ = 0) took place at rates ~0.2 that of quenching.