Molecular Force Fields of Ethylene, Allene, Formaldehyde, Ketene, and Diazomethane

Infrared and Raman spectra furnish one of the most powerful methods for studying the internal forces which act in molecules. The vibrational frequencies which are obtained from a study of the spectra are functions of the geometry and masses, which determine the kinetic energy of the system, and of the forces acting in the molecule, which determine the potential energy of the system. Therefore, if the geometry of a molecule is known, the vibrational frequencies of the molecule can be used to ob­tain information concerning the forces acting during the motions.