Fluorescence lifetime studies of no a 2Σ +(ν = 5, N = 9), B 2Π [formula omitted](ν = 8, J = 8.5), C wΠ [formula omitted](ν = 1, J = 8.5), D 2Σ + (ν = 0, N = 5) and D 2Σ +(ν = 1, N = 9)

Abstract

Fluorescence decay profiles of NO excited levels slightly above the dissociation limit have been measured by a single-photon counting technique with nanosecond pulse excitation using an iodine flash lamp. Three iodine atomic lines in the vicinity of 180 nm are found to bring NO molecules into the levels A 2Σ +(ν = 5, N = 9), B 2 2Π 3 2 (ν = 8, J = 8.5), C 2Π 3 2 (ν = 1, J = 8.5), D 2Σ +(ν = 0, N = 5) and D 2Σ +(ν = 1, N = 9). Extrapolated zero-pressure lifetimes for single rotational levels are obtained, except for the C state where only a lifetime of ⩽0.4 ns was obtained. Self-quenching rate constants are also determined under higher-pressure conditions. Helium was found to quench the NO A 2Σ +(ν′ = 5) fluorescence very efficiently.