The atoms of a molecule can vibrate in many waysthese are
called the normal modes of vibration. The normal modes have different excitation
energies so the Raman spectrum will consist of more than one line. The number
of normal modes is easily deduced; if the number of nuclei in the molecule is
N, then the total number of degrees of freedom (i.e., the number of coordinates
required to specify the positions of all of the nuclei) is 3N. Of these, three
account for translation of the molecule as a whole and three more for its
rotation. So the third is 314 nm
