Ionising vs Non Ionising Radiation
Radiation is the process where waves or energy particles (e.g. Gamma rays, x-rays, photons) travel through a medium or space. Radioactivity is the spontaneous nuclear transformation that results in the formation of new elements. In other words, radioactivity is the capability to release radiation. There are a large number of radioactive elements. In a normal atom, the nucleus is stable. However, in the nuclei of radioactive elements, there is an imbalance of neutrons to protons ratio; thus, they are not stable. To become stable, these nuclei will emit particles, and this process is known as radioactive decay. These emissions are known as radiation. Radiation can be either ionizing or non-ionizing.
Ionizing radiation has high energy, and when it collides with another atom, it will be ionized, emitting another particle (e.g. an electron) or photons. The emitted photon or particle is radiation. The initial radiation will continue to ionize other materials until all its energy is used up. Alpha emission, beta emission, X-rays, and gamma rays are ionizing radiations. Alpha particles have positive charges, and they are similar to the nucleus of a He atom. They can travel across a very short distance (i.e. few centimeters) and they travel in a straight path. They interact with the orbital electrons in the medium through Coulombic interactions. Because of these interactions, the medium gets excited and ionized. At the end of the track, all alpha particles become He atoms. Beta particles are similar to electrons in size and charge. So, repulsion takes place equally when they are travelling through the medium. A large deflection in the path happens when they encounter electrons in the medium. As this happens, medium gets ionized. Beta particles travel in a zigzag path and can travel a longer distance than alpha particles. Gamma and x-rays are photons, not particles. Gamma rays are produced inside a nucleus, and x-rays are produced in an electron shell of an atom. Gamma radiation interacts with the medium in three ways as photoelectric effect, Compton Effect, and pair production. Photoelectric effect is more probable with tightly bond electrons of atoms in medium and low energy gamma rays. In contrast, Compton Effect is more probable with loosely bound electrons of atoms in the medium. In pair production, gamma rays interact with atoms in the medium and produce electron positron pair.
Non-ionizing radiations do not emit particles from other materials, because their energy is lower. However, they carry enough energy to excite electrons from ground level to higher levels. They are electromagnetic radiation; thus, have electric and magnetic field components parallel to each other and to the wave propagation direction. Ultra violet, infrared, visible light and microwave are some of the examples to non-ionizing radiation.
What is the difference between Ionizing Radiation and Non-ionizing Radiation?
• Ionizing radiation has high energy than the non-ionizing radiation.
• Therefore, ionizing radiation can emit electrons or other particles from atoms when they collide. However, non-ionizing radiation can only excite electrons from a lower level to a higher level upon encountering.
• UV, visible, IR, microwave and radio waves are categorized as non-ionizing radiation, whereas alpha, gamma, and X rays can be categorized as ionizing radiation.