Infra-Red Bands of Methylamine and the Phenomenon of Free Rotation

Abstract

Two bands in the absorption spectrum of methylamine have been measured in the photographic infra‐red. One of the bands shows rotational structure. The bands have been interpreted as involving excitation of the frequencies 3ν_CH+ν_CN). The rotational structure of the latter band suggests that it is a perpendicular‐type band, and the precise spacing of the Q branches suggests that the molecule behaves approximately like a rigid symmetric top. The inference of hindered internal rotation is in agreement with other independent data.