Electromagnetic Radiation and its Applications in Scientific Research

Electromagnetic Radiation

Electromagnetic radiation is a form of energy which is produced by oscillating electric and magnetic disturbance, or by the movement of electrically charged particles, such as electron, travelling through a matter or free space.

 In the quantum mechanical terms, electromagnetic radiations are propagated in discrete packets of energy, called photon, which are bundles of light energy that travel at the speed of light as quantized harmonic wave. The energy of photon is derived by the relationship, E = h ʋ. This energy is then grouped into categories based on its wavelength into the electromagnetic spectrum.

Waves and their Characteristics

EM radiation is so-named because it has electric and magnetic fields that simultaneously oscillate in planes mutually perpendicular to each other and to the direction of propagation through space and have certain characteristics, including amplitude, wavelength, and frequency.

Cosmic ray, gamma rays, x-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves are examples of electromagnetic radiation, and they differ in frequency and wavelength.
 Sources of electromagnetic radiation of specific frequency are atom or molecule. Since all of the energy states of a atom or molecule are quantized, therefore, atom or molecule undergo a transition from lower energy state to a higher energy state by irradiation with EM radiation. When the atom or molecule returns back in lower state, an equivalent amount of energy is emitted. Thus excitation of an organic molecule involves absorption of specific quanta of EM radiation when energy of photon corresponds exactly to an energy difference between the two states of the molecule. The range of all EM frequencies is known as the electromagnetic spectrum, is the distribution of electromagnetic radiation according to energy or wavelength or frequency.

Electromagnetic spectrum 

                                  

Types of Electromagnetic Radiation: 

There are two forms of radiation - non-ionizing and ionizing. 

 Non-ionizing radiation 

 Non-ionizing radiation has less energy than ionizing radiation; Such as visible light, infrared, radio waves, microwaves, and sunlight.

Ionizing radiation

 Ionizing radiation is capable of knocking electrons out of their orbits around atoms, upsetting the electron/proton balance and giving the atom a positive charge and includes the radiation that comes from both natural such as Cosmic, Terrestrial radiation, Inhalation, Ingestion and man-made radioactive materials such as Medical and Industrial   sources, Nuclear fuel cycle, Atmospheric testing. Alpha (α), Beta (β), Photon (gamma [γ] and X-ray) and Neutron radiation (n) are some ionizing radiation.

Characteristic of electromagnetic radiation: 

The characteristic of electromagnetic radiation occurs in different EM spectrum region are described below:

Cosmic Radiation:

Cosmic radiation, a source of natural radiation that originates in outer space. It composed of penetrating ionizing radiation (particulate and electromagnetic). The Earth’s magnetic field deflects charged cosmic rays towards the poles. If we confirm ourselves to the particle constituents, most of the cases their motion in the galaxy has been roughly randomized by the galactic magnetic field. Thus they provide very little information about the direction of the source. The peak of the distribution in energy is in the range of 100 MeV–1 GeV. The composition has been measured by instruments mounted on balloons, satellites, and space-craft.

Gamma Radiation

Gamma radiation is a penetrating EM radiation emitted by an atomic nucleus during radioactive decay; a high-energy, short wavelength form of ionizing radiation and also produced the Sun and other stars. Gamma ray photons are between 10,000 to 10,000,000 times more energetic than the visible light photons. Gamma rays with a million times higher energy make up a very small part of cosmic rays. Doctors can also use gamma rays to kill cancer cells and fight tumours.  Astronomical sources emitting in gamma range of the electromagnetic spectrum, Matter falling into black holes.

X-RAYS

X-rays emitted by an atom when it has been bombarded with electrons. X-rays differ from gamma rays in that they are emitted from the orbiting electrons, not the nucleus and are typically lower in energy than gamma radiation. X-rays are produced mainly by artificial means, rather than from radioactive substances, and are used mainly for medical purposes.

Ultraviolet Radiation

Ultraviolet radiation is part of the EM spectrum and lies between the visible and the x-ray region and its wavelength lies between 400 and 200nm. Since these waves can damage our skin and eyes, hence, Sun block and UV-protection sunglasses are designed to filter out these frequencies. UV light can be used to sterilize medical instruments and food by killing harmful bacteria and also UV light causes skin cells to produce vitamin D, which is essential to good health. 

Visible Radiation

Visible light constitute the major fraction of solar radiation reaching the atmosphere of the Earth. Approximately 40 % of the radiation energy is visible light of wavelengths between 400 nm - 800 nm. It is the only part of the EM spectrum that humans can see with an unaided eye. This includes a range of different colours of the longest wave length as red and the shortest as violet. Firefly, light bulb, stars etc. all Emits visible light.

Infrared Radiation

It consists of EM frequencies between microwaves and visible light and the range of frequency is, 4000 per cm- 600 per cm. IR radiation most often associated with heat, sometimes called heat rays. Although we can’t see it, we can feel it as warmth coming from the Sun, fire or radiator. Infrared lamps are used to provide warmth in bathrooms and to keep food warm and in cook food and also used in remote sensing as infrared sensors collect thermal energy, providing us with weather conditions. However, infrared scopes and cameras convert infrared radiation into visible wavelengths. This technology can create useful images of objects. Some source of IR radiation as LEDs, LASERs.

Microwaves

Microwaves have higher frequencies, energy than radio waves and lower than IR rays. Microwaves can be used to broadcast information through space, also used in remote sensing in which microwaves are released and bounced back to collect information on their reflections. They are good for transmitting information because the energy can go through substances such as clouds and light rain. Short microwaves are sometimes used in Doppler radars to predict weather forecasts. Two important technologies that use microwaves are radar (Today, it used to control air traffic, analyze weather conditions) and cell phones.

Radios waves

Radios waves are approximately 10³ m in wavelength and are transmitted by radio broadcasts, TV broadcasts, cell phones Their frequencies range from 300GHz to as low as 3kHz and have the lowest energy. Radio wave of EMR, are used for wireless transmission of sound messages, aircraft navigations, remote sensing. Especially useful in weather, radar systems are used to can illustrate maps of the surface of the Earth and predict weather patterns.

Applications of electromagnetic radiation in scientific research

The various forms of EM energy have now becomes familiar terms such as x-ray used in medicine, UV rays lead to sunburns and radio waves as communication.

In Radiation chemistry: 

Radiation chemistry, studies chemical transformations in materials exposed to high energy radiations. It does not deal with radioactive elements, except to use them as a source of radiation. Researcher are interested in electromagnetic (X-rays, gamma rays), charged particles (electrons, positrons, protons), neutral particles (neutrons). Its scientific applications today extend to many fields, including health care, food and agriculture, manufacturing, and telecommunications. The important advantage of radiation lies in its ability to be used to produce, almost any reactive atomic species playing a part in chemical reactions, synthesis, industrial processes, or in biological systems.

In Nuclear chemistry: 

Radiation is essential for understanding and control of processes in nuclear reactors where water is used as moderator and coolant and, of course, subject to radiolysis. We can produce a large amount electricity under the fission Nuclear substance Practical applications of radiation have become far-reaching, particularly in industry and specific area of interest has been in radiation modification of polymers for different uses such as radiation cross linking of polymers, Radiation sterilization, Radiation curing.

In Medical uses:

The EMR are especially useful in the field of medicine. Such as radiofrequency used in MRI scanner and RAF (uses heat to destroy cancer cells). It also used to produce image of soft tissues, fluid, fat and bone and also used to diagnose many problem e.g. helps in identify the tumours. Cancer cells being targeted by microwave, Infrared is used in locating tumours. The use as contrast media, fluorescent screens, image intensifiers, and the use of digital technology to all x-ray systems.

In spectroscopic technique: 

Several spectroscopy such UV-visible, IR, NMR, Mass, microwave, Raman spectroscopy etc., requires EM radiation of different energy which gives several information about compound such as structure and properties.

New emerging applications: 

It include radiation treatment of flue gases from coal- and oil-fired power plants to remove toxic components, sulphur dioxide, and nitrogen oxide, for purposes of environmental protection. Treated products can be converted into agricultural fertilizer. In other research, a series of biomedical applications are being developed using radiation modification of polymer surfaces or immobilization of different biologically active material.

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