Spectroscopy (Chemistry)

This week i was lucky enough to attend a university lecture on chemistry particularly spectroscopy and its various uses in the world. Spectroscopy is the study of the interaction between electromagnetic radiation and matter, with measurements being taken by a spectrometer. It is commonly used in laboratories to obtain valuable information on the makeup of molecules and the various bonds in different molecules.

There is no one universal spectrometer to obtain information of molecules, with a variety of multiple techniques being used in chemical labs to gain a better understanding of the makeup of different molecules. Currently most of the components of the electromagnetic spectrum are used in different spectrometry techniques with nuclear magnetic resonance spectroscopy (NMR) using radio waves, microwave spectrometry using microwaves, infrared spectroscopy, colorimetry using light waves, uv-visible spectroscopy using UV waves and crystallography using x-rays (there is currently no spectroscopy using gamma rays).

The first type of spectroscopy i learnt about was mass spectroscopy that does not use any type of electromagnetic radiation and instead uses high energy electron beams to knock off an electron from atoms to create positively charged ions that can be accelerated and deflected (using magnetic fields) in a mass spectrometer to detect their quantities using a detection plate (whereby a current is created by charged particles hitting the detection plate to provide the relative abundance of each different type of atom (ie isotopes) and molecules). Mass spec provides the molecular formula of a compound.

Another type of spectrometry is infrared spectrometry which uses infrared waves to detect the type of covalent bonds in a molecule. Infrared waves pass through a molecule and cause covalent bonds in the molecule to vibrate, with each type of bond vibrating by different amounts allowing it to be identified easily. Individual molecules can be identified using the fingerprint region of the the spectrum.


NMR (nuclear magnetic resonance) is the use of different nuclear structures to detect different bonds within a molecule. It provides a quantitative value by the area of peaks and provides an indication of the environment of each bond by the position of the bond on the spectrum.