Microwave Spectrum of Fluoro-Acetonitrile

Abstract

FLUORO-ACETONITRILE (FCH₂CN) is a molecule of some structural interest which is well suited to microwave study, all nuclei being well removed from the molecular centre of gravity in a structure of considerable dipole moment. It should thus be possible to locate the atoms of the —CH₂CN group accurately with respect to the mass centre, by the method of isotopic replacement, and hence also to determine the position of the fluorine atom. As part of such an investigation, we report an assignment of the spectrum of the principal isotopic form. Transitions of the R-branch corresponding to the A-component of the molecular dipole have been identified for J = 0 → 1, 1 → 2, 2 → 3 and 3 → 4, between 9 and 38 Gc./s.; Q-branch lines for the same component, J_1,J → J_1,(J−1), have been assigned for J = 6, 9, 10, 11 and 12. Corresponding to the B-component of the dipole, lines of the type J_0,J → J_1,(J−1) have been measured for J values of 1–5.