Infrared spectroscopy is a spectroscopy that detects IR rays having longer wavelength and lower frequency than visible rays among the electromagnetic radiant rays. When shooting infrared light on a molecule, a particular frequency of light is absorbed onto the molecule. Most of functional groups absorb a particular range of infrared light. After detecting what frequency of light a molecule absorbs in IR spectrum, it is used to understand the functional groups and characteristics of the molecule.
Vibrational Circular Dichroism Spectroscopy is a spectroscopy that detects the difference in absorption. It is based on the phenomenon that the degree of absorption varies depending on the direction of polarization in a molecule when shooting polarized infrared light on it. From this, it is possible to determine the structural characteristics of a molecule, analyze the 3-dimentional singularities of chiral molecules, measure the purity of mirror image isomer (antipode), and monitor asymmetric reaction.
Nuclear Magnetic Resonance Spectroscopy checks the interaction between the nucleus and the magnetic field when placing a molecule in an external magnetic field. If electromagnetic wave is transmitted to the sample inside a magnetic field, the sample will absorb microwaves with specific wavelengths. This will result in obtaining a spectrum from resonance absorption. This method is used to verify the structure, electromagnetic characteristics or other chemical properties of a compound.