Infrared Spcetrometry

Introduction:

Exposure of a molecule to infrared radiation results in vibration which produces stretching, bending or rotation of bonds.  If these vibrations result in change in dipole moment, infrared absorption occurs.  this is characterised by sharp absorption bands in contrast to the rather broad bands given in the UV and visible regions of the electromagnetic spectrum.  These vibrational effects can be visualised to some extent by constructing a model using sprongs for bonds and balls for atoms.  If the suspended model is struck, the balls will agitate violently.  When the model is subjected to stroboscopic light of variable frequency it is seen that at certain frequencies some of the ballls will appear stationary.  This result represents the normal vibrational modes and corresponding frequencies.

Use of IR Spectrometry:  The technique has become very useful in identification of substances and for the study of molecular structure and composition.  IR Spectrometry is rarely used for quantitative work.  Its main use in clinical laboratory is in the area of renal stone analysis.

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