Knowledge Bank

In the infrared spectra of $CH3NF2$ and $CD3NF2$ the bands corresponding to the unsymmetric methyl-group motions have complex structures which are not consistent with expectation on the basis of $C2$ symmetry. They are interpreted as the consequence of rotational coupling between the nearly-degenerate $A\prime$ and $A″$ components of these vibrations. The observed bands are compared with those expected, and the effect of deuteration on band features is considered.