Knowledge Bank

Samples of formyl fluoride and of deuterated formyl fluoride have been examined in the region 2.5 to 25 microns with a Perkin-Elmer double-pass prism spectrometer. Of the six expected fundamentals, for a molecule of point group $CS$ there are five planar vibrations of species $A\prime$ and one nonplanar vibration of species A"". All vibrations of the first species have been assigned. No satisfactory assignment could be made, however, for the remaining non-planar fundamental. The assigned frequencies for the two isotopic molecules satisfy the Teller-Redlich product rule. From frequencies and intensities, there is indication of Fermi resonance occurring between $\nu (C-Fstretch)$ and $\nu C-Dbend$ in the deuterated compound. A normal coordinate treatment of the molecule will be discussed.