The silent features of the book titled ?Applications of Spectroscopy? is that the Normal Co-ordinate Analysis of high temperature super conductors have been analysed by spectroscopic method. Here it is enlighted that normal modes of oscillation belongs to unirreduciable representation of the group symmetry operation. One of the main objectives of the phonon frequency vibrational spectra of polyatemic molecules are the investigation of the nature of the force under equilibrium position. Here the spectroscopy deals with Raman and infrared transition which shows the scattering and absorption process. The fundamental frequencies and the normal co-ordinate corresponding to the potential and kinetic energies of the particles. Further this leads better understanding of phonon frequency of high temperature super conductors and the normal co-ordinate analysis of the optically active vibrations is useful for the theoretical interpretation of the vibrational spectra in cuparate oxide.