Chemistry Notes for B.Sc. and M.Sc.

The principle of IR Spectroscopy states that the absorption of IR radiations occurs only by those vibrations of bonds in a molecule which are accompanied by change in dipole moment  Only those wavelength of IR radiations are absorbed which have similar energy as that of quantized vibrational energy levels of that molecule. The vibrational transitions are also accompanied by rotational transitions of the molecule. The amount of energy or the stretching vibrational frequency of any bond can be calculated using hooke's law which states that ν  =1/2π√(k/µ) k = force constant µ = reduced mass  The reduced mass of any bond is given by: µ = m 1 .m 2 /m 1 +m 2 m 1 and m 2 are the mass of atoms joined by bond.