**3.3 Spectroscopic methods**

Various spectroscopic techniques such as Raman, nuclear magnetic reso¬nance (NMR), Fourier transform (FT-IR) infra-red spectroscopies, terahertz (THz) spectroscopic imaging, and various advanced applications of these methods are in practice to investigate the structure of co-crystals and find out the intermolecular forces between the components of co-crystals [45, 46].
