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Infrared radiation |
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The discovery of Infrared radiation is credited to the astronomer, William Herschel, in the early 19th century. Herschel published his results in the year 1800 before the UK Royal Society. Using a prism to refract light from the sun he detected the Infrared, beyond the red part of the spectrum, through an increase in the temperature recorded on a thermometer. Surprised at the result Herschel called them the "Calorific Rays". The word 'Infrared' did not appear until late in the 19th century. Even though Infrared radiation is not observable, humans can still sense it as ‘heat’. Putting ones hand next to a hot oven will make the person experience Infrared radiation first-hand!
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Infrared radiation or IR as it is known is an electromagnetic radiation of a wavelength longer than that of visible light, but again shorter than that of microwaves. The name IR usually means ‘below red’ derived from the Latin word infra, ‘below’, red being the color of noticeable light with the longest wavelength. Spanning five orders of magnitude, the Infrared radiation has wavelengths between about 750 nm and 1 mm. There are various ways the Infrared radiation can be used in our daily lives.
One use of Infrared radiation is the Infrared imaging, used widely for both military and civilian purposes. Military applications include surveillance, target acquisition, homing and tracking and non-military uses comprise of thermal efficiency analysis, spectroscopy, short-ranged wireless communication, remote temperature sensing, and weather forecasting. The astronomers use the Infrared for sensor-equipped telescopes to penetrate dusty regions of space, such as molecular clouds; to view highly red-shifted objects from the early days of the universe and detect cool objects such as planets.
At the atomic level, the infrared energy draws out vibrational modes in a molecule through a change in the dipole moment, making it a useful frequency range for studying these various states of energy. While Infrared spectroscopy scrutinizes the absorption and transmission of photons in the infrared energy range, based on their frequency and intensity. Objects generally emit Infrared radiation across a spectrum of wavelengths, but only a particular region of the spectrum is of interest because sensors are generally designed only to collect radiation within a specific bandwidth and not other wise. Accordingly, the infrared band is often subdivided into numerous smaller sections.
The radiation in the Electromagnetic Spectrum is often classified by wavelength. Short wavelength Infrared radiation is of the highest energy and can be quite dangerous like the Gamma, X-rays and ultraviolet are examples of short wavelength radiation. On the other hand, longer wavelength radiation is of lower energy and is usually less harmful for examples it includes microwaves, radio and infrared. A rainbow shows the optical (visible) part of the Electromagnetic Spectrum and infrared (if you could see it) would be located just beyond the red side of the rainbow.
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