Infra Red Spectropscopy (IR spectroscopy)
Infra red has long wavelength and less energy than UV and visible spectrum. It is associated with vibrational transition but not with the electronic transition. Infrared radiation stimulates molecularvibrations and absorption of radiation by a sample is due to changes in the vibration energy states of a molecule. Frequency of the incident radiation is varied and the quantity of radiation absorbed or transmitted by the sample is obtained.The spectra are represented as percent transmittance versus wave number.
It is useful in identifying functional groups of a compound.
· Stretching of bonds, bending of bonds, or internal rotation around single bonds can be revealed.
· The measurement of the type and amount of light transmitted by the sample gives information about the structure of the molecules comprising the sample.