The term spectrum refers to the bands into which electromagnetic radiation can be split or resolved. By the study of spectrum, matter and energy is investigated. The study of spectroscopy deals with emission as well as absorption spectra.
Emission spectrum is produced by the emission of radiant energy by an excited atom. When an atom is thermally or electrically excited, electrons in the ground state is promoted to metastable states. When electrons from the metastable state jump to the lower energy state, some energy is released as radiation which is analysed with the help of a spectroscope.
Absorption spectrum is produced by the absorption of radiation of a certain wave length which characterise a particular functional group or a copmound. After absorption the transmitted light is analysed by a spectrometer. Dark pattern of lines corresponding to the wavelengths absorbed is obtained which is the absorption spectrum.
The types of spectroscopy depends on the physical quantity measured, ie; normaly the intensity of energy absorbed or produced.
- Electromagnetic spectroscopy involves interaction of matter with electromagnetic radiation.
- Electron spectroscopy involves interactions with electron beams.
- Mass spectroscopy involves interaction of charged species with magnetic or electric field.
- Acoustic spectroscopy involves the frequency of sound.
- Mechanical spectroscopy involves the frequency of an external mechanical stress.
- Dielectric spectroscopy involves the frequency of an external electric field.