Knowledge Bank

The high resolution infrared spectra of three fluorobenzene isotopes (normal-, pentadeutero-, and paradeutero-) were obtained and interpreted. Using the homology among isotopes as a guide, an accurate determination of most of the fundamental vibrations was made. The $a2$ vibrations were particularly interesting in this respect. The invariance of these vibrations between the normal- and paradeutero- isotopes allowed determination of their values with certainty from their appearance in combination and overtone bands. Other significant results of this work include major reassignments of fundamentals from previously reported values.