The structure of the Goldstein-Kaplan bands of N 2

Abstract

Three bands of the Goldstein-Kaplan system of N₂ have been photographed under high resolution and rotational analyses made. It is shown conclusively that the blue-green Goldstein bands and the ultra-violet Kaplan bands form a single system having the well-known B³Π_g state as the lower level. The upper state, C', is identified as ³Π_u with the rotational constants B₀ = 1·0496 cm^-1, D₀ = 10·9 x 10^-6 cm^-1, H₀ = 8·3 x 10^-10 cm^-1. The state shows case b coupling and has an unusual structure in which spin-spin interaction appears to play an important part. To account for the unusual properties of the state it is suggested that it arises from a mixture of two or more molecular orbital configurations. The vibrational structure indicates either that predissociation occurs or that the state has a small dissociation energy. The interaction of the C´ and C states is discussed and is suggested to be responsible for the observed irregularities in the C³Π_u state.