Difference Between Ionising and Non Ionising Radiation

The key difference between ionising and non ionising radiation is that Ionizing radiation has high energy than the non-ionizing 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. Hence, to become stable, these nuclei will emit particles, and this process is known as radioactive decay. These emissions are what we call radiation. Radiation can occur as either ionising or non ionising form.

CONTENTS

1. Overview and Key Difference
2. What is Ionising Radiation
3. What is Non Ionising Radiation
4. Side by Side Comparison – Ionising vs Non Ionising Radiation in Tabular Form
5. Summary

What is Ionising Radiation?

Ionising radiation has high energy, and when it collides with an atom, the atom undergoes ionisation, emitting another particle (e.g. an electron) or photons. The emitted photon or particle is radiation. The initial radiation will continue to ionise other materials until all its energy is over. Alpha emission, beta emission, X-rays, and gamma rays are types of ionising radiation.

There, alpha particles have positive charges, and they are similar to the nucleus of a Helium atom. They can travel across a very short distance (i.e. few centimetres), and they travel in a straight path. Moreover, 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 Helium atoms.

Figure 01: Hazard Symbol for Ionising Radiation

On the other hand, beta particles are similar to electrons in size and charge. Therefore, repulsion takes place equally when they are travelling through the medium. A large deflection in the path occurs when they encounter electrons in the medium. As this happens, medium gets ionized. Furthermore, the beta particles travel in a zigzag path; thus, they can travel a longer distance than alpha particles.

However, gamma and x-rays are photons, not particles. Gamma rays form inside a nucleus while x-rays form in an electron shell of an atom. Gamma radiation interacts with the medium in three ways as the photoelectric effect, Compton Effect, and pair production. The photoelectric effect is more probable with tightly bond electrons of atoms in medium and low energy gamma rays. In contrast, the 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.

What is Non Ionising Radiation?

Non ionising radiation does not emit particles from other materials, because their energy is low. 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 the wave propagation direction.

Figure 02: Ionising and Non ionising Radiation

Moreover, Ultraviolet, infrared, visible light and microwave are some of the examples of non ionising radiation.

What is the Difference Between Ionising and Non Ionising Radiation?

The emission of particles forms unstable nuclei of radioactive elements is what we call radioactive decay. This particles emission is the radiation. There are two types as ionising and non-ionizing radiation. The key difference between ionising and non ionising radiation is that Ionising radiation has high energy than the non ionising radiation.

As another important difference between ionizing and non ionising radiation, ionising radiation can emit electrons or other particles from atoms when they collide while non ionising radiation cannot emit particles from an atom. There, it can only excite electrons from a lower level to a higher level upon encountering.

Summary – Ionising vs Non Ionising Radiation

Radiation is the process where waves or energy particles travel through a medium or space. The key difference between ionising and non ionising radiation is that ionising radiation has high energy than the non ionising radiation.

Reference:

1. “Nuclear Chemistry.” Transition Metals. Available here

Image Courtesy:

1.”Radioactive”By Cary Bass (Public Domain) via Commons Wikimedia  
2.”NonIonizingRadiation”By Glenna Shields (Public Domain) via Commons Wikimedia 

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