This technique covers the region of the electromagnetic spectrum between the visible (wavelength of 800 nanometres) and the short-wavelength microwave (0.3 millimetre). The spectra observed in this region are primarily associated with the internal vibrational motion of molecules, but a few light molecules…

The infrared spectrum of an organic compound, with its complexity of bands, provides an excellent “fingerprint” of the compound—far more characteristic than a melting point. It also can be used to identify certain common groups, such as carbonyl (C=O) and imino, as well as various heterocyclic…

In organic compounds, atoms are said to be bonded to each other through a σ bond when the two bonded atoms are held together by mutual attraction for the shared electron pair that lies between them. The two atoms do not remain…

For this reason, infrared spectroscopy is a powerful tool for determining the internal structure of molecules and substances or, when such information is already known and tabulated, for identifying the amounts of those species in a given sample. Infrared spectroscopic techniques are often used to determine the composition…

Vibrational spectroscopy shows that isotopically heavier diatomic molecules have higher bond energies. (Bond energy is the amount of energy needed to separate the two atoms.) Quantum mechanical theory makes it possible to calculate from vibrational spectra just how much stronger the bond to the heavier…

…the observation of a vibrational spectrum for a diatomic molecule are the occurrence of a change in the dipole moment of the molecule as it undergoes vibration (homonuclear diatomic molecules are thus inactive), conformance to the selection rule Δv = ±1, and the frequency of the radiation being given by…