Spectroscopy: Electromagnetic Radiation

Spectroscopy deals with the production, measurement and interpretation of spectra due to interaction of electromagnetic radiation with matter which is absorbed or emitted by atoms of a sample. This absorption or emission occurs when the atoms of the sample move from one energy level to another in presence of light. In other words, it is a science which deals how light interacts with matter. When atoms or molecules absorb electromagnetic energy, the incoming energy promotes the molecular system to a higher energy level. Electrons are promoted to higher orbitals by ultraviolet or visible light, vibrations due to infrared light and rotations due to microwaves. Electromagnetic radiation can be transmitted, absorbed or reflected by matter and each

white light) is allowed to fall on a substance, then the frequencies absorbed by the substance are studied. This type of spectrum is an absorption spectrum and called an absorption spectroscopy. The spectrum shows that the light separated into its constituent wavelength and intensity plotted at each wavelngth. This separation process is known as Spectroscopy. In spectroscopy the emitted or absorbed radiation is split into the various frequency components and the intensity is measured by means of an instrument called a spectrometer. The resultant spectrum is usually a graph of intensity of emitted or absorbed radiation versus wavelength or frequency. The spectra used in spectroscopy varies from ultra-violet, visible, infra red ranges. The wavelength range for the three spectra are 0-400, 400-700 and above. In short, spectroscopy use to gain insight into the structure of molecules or the concentration of atoms or molecules in a sample. The chemists use infrared radiation to determine the structure of a new molecule, geologists uses ultraviolet radiation to determine the concentration of particular element in rock or

It has been used to make significant contributions in many areas of physics and chemistry as well as in other areas of science. FTIR (also known as mid-IR) is the most commonly used vibrational technique for identification of material and authentication[]. Its applications include identification of functional groups or compound identification, determination of the strength of chemical bond and the calculation of thermodynamical properties. If one can obtain all the vibrational information from the molecule, its molecular structure can be determined. In the field of spectroscopy, two major techniques are used to detect molecular vibrational motions: Infrared spectroscopy and Raman spectroscopy. Infrared Spectroscopy is simply the analysis of infrared light interacting with a molecule. During infrared spectroscopy we observe transitions between vibrational energy levels of a molecule by the absorption of infrared (IR) radiation. IR spectroscopy is the powerful and analytical tool in identification, estimation, and structure determination of compounds and being able to identify the various vibrational modes of a molecule. When a molecule absorb IR radiations, the vibrations or rotations within a molecule must cause a change in the dipole moment of the molecule. During the vibrational motion of a molecule, a regular fluctuation in the dipole moment occurs and a field