Spectroscopy

Spectroscopy

When we have an unknown compound, we need to identify it with spectroscopy. Spectroscopy is a general term used for the instrumental processes by which information about the molecular structure is obtained through careful analysis of the absorption, scattering, or emission of electromagnetic radiation by compounds. Structure identification of compound can be divided into three types of spectroscopy based on the principles, such as ultraviolet spectroscopy, infrared spectroscopy, and NMR spectroscopy.

Identification of the unknown compounds can be analyzed by using ultraviolet Spectroscopy. The ultraviolet spectrum of the unknown compounds will absorb in the UV-Vis wavelength range (λ_maks). The spectrum will absorb at a given wavelength and this property is due to functional groups, conjugation, etc. UV-Vis can be used in a qualitative manner, to identify functional groups or confirm the identity of a compound by matching the absorbance spectrum. It can also be used in a quantitative manner, as the concentration of the analyte is related to the absorbance using Beer's Law.

Identification of the functional group determined based on the analysis of infrared spectroscopy. An infrared spectrophotometer is an instrument that passes infrared light through an organic molecule and produces a spectrum that contains a plot of the amount of light transmitted on the vertical axis against the wavelength of infrared radiation on the horizontal axis. Infrared spectroscopy is therefore extremely useful for determining the types of functional groups present in organic molecules.

NMR spectroscopy is one of the most useful analytical technique for determining the structure of an organic compound. There are two kinds of NMR spectroscopy, such as proton magnetic resonance and carbon magnetic resonance. Proton NMR spectra yield a great deal of information about molecular structure because most organic molecules contain many hydrogen atoms, and the hydrogen atoms absorb the energy of different wavelengths depending on their bonding environment. Carbon NMR is possible, and the technique provides valuable information about the structure of the carbon skeleton in organic molecules.

Spectroscopy is used in physical and analytical chemistry because atoms and molecules have unique spectra. As a result, these spectra can be used to detect, identify and quantify information about the atoms and molecules. Identifying compounds can be done with spectroscopy analysis including UV-vis spectroscopy, IR spectroscopy, and NMR spectroscopy.