A- and C-type bands in the infra-red spectrum of pyrrole

Abstract

The rotational fine structure of the 3ν₁ and ν₂₂ vibrations of pyrrole (C₄H₅N) have been recorded at 0.98 and 14 µm respectively. About 100 lines were measured in the 3ν₁ and 120 in the ν₂₂R- and P-branches. The analysis of the resolved fine structure and of the Q-branch contour yielded the following molecular constants (all in cm^–1): A′= 0.304 5, B′= 0.298 5, C′= 0.151 22, ν₀= 10 184.174 for 3ν₁, and B′= 0.301 4, ν₀= 722.21 for ν₂₂. The rotational levels of 3ν₁ with 35 < J < 45 are perturbed and the fine structure is either weak or not observed in this range of J-values.