File:Chapter-16 Infrared spectroscopy (Theory & Principle) pp 148-150.pdf

Molecular Vibrations be the basic principle of the IR spectra. Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) involves the interaction of infrared radiation with matter. It covers a range of techniques, mostly based on absorption spectroscopy. As with all spectroscopic techniques, it can be used to identify and study chemical substances. Samples may be solid, liquid, or gas. The method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer (or spectrophotometer) to produce an infrared spectrum. IR radiation corresponds to the energy required to make chemical bonds vibrate more / move to a higher vibrational energy level. Therefore, energy of certain wavelengths is absorbed by molecules. The actual energy depends on the mass of the atoms and the strength of the bond, so different bonds will absorb at different frequencies. Stronger bonds (higher Electro negativity difference) need more energy to make them vibrate, so absorb a higher frequency of i.r. radiation (higher wave number).