In 1986, under Prime Minister Rajiv Gandhi’s leadership, the Indian government declared February 28 as National Science Day to honor Dr. C.V. Raman’s groundbreaking discovery, the Raman Effect. On this day in 1928, he officially shared his findings with the scientific community, marking a significant milestone in physics.
His discovery helped scientists understand how light behaves when it passes through different materials. National Science Day is celebrated every year to honor this achievement and to encourage interest in science and technology.
Physicist Sir C.V. Raman won the Nobel Prize in 1930 for making this important discovery.
Using a straightforward experiment, Raman found that when light passes through a liquid, a small part of the scattered light changes color.
Scientists quickly recognized this discovery as a major breakthrough, leading to over 700 research papers on it within just seven years.
What is the Raman Effect, and why does it matter? More importantly, who was the brilliant mind behind this groundbreaking discovery?
Raman’s Journey: Scholar to Scientist
Raman was born in 1888 in Trichy (now called Tiruchirapalli), in the Madras Presidency, into a family of Sanskrit scholars.
When he was just 16, he earned a BA degree from Presidency College in Madras and placed first in his class.
At just 18, while working on his MA degree, he published a research paper in the Philosophical Magazine. It was the first-ever research paper from Presidency College.
Because of his poor health, he couldn’t go abroad for further studies. So, in 1907, he got married and moved to Calcutta, where he worked as an assistant accountant general.
Even while working full-time as a civil servant, Raman spent his free time doing research at the Indian Association for the Cultivation of Science (IACS).
Raman helped make IACS more well-known by conducting some award-winning research and giving engaging public demonstrations.
At 29, he left his civil service job and became a professor at Presidency College in Calcutta.
By 1921, CV Raman was well known as a brilliant scientist, both in India and abroad.
That year, he traveled to England for the first time. On his way back, he made an observation that would change both his life and the world of science forever.
As he traveled across the Mediterranean Sea, Raman was amazed by its deep blue color.
Unhappy with the common belief that the sea’s color was just a reflection of the sky, he became even more curious and decided to explore further.
Raman soon discovered that the sea’s blue color was not just a reflection of the sky, as many people believed. Instead, he found that sunlight was scattered by tiny particles in the water (water molecules). This scattering caused the blue light to spread more than other colors, making the sea appear blue to our eyes.
Water is made up of tiny particles called water molecules, each consisting of two hydrogen atoms and one oxygen atom (H₂O). These molecules join together to form liquid, solid, or gaseous water.
Curious about how light spreads, Raman and his team in Calcutta did many experiments. Their hard work led to an important discovery, now called the Raman Effect.
The Raman Effect
The Raman Effect occurs when light passes through a liquid, and some of the scattered light changes color. This happens because the light interacts with the molecules in the liquid, which alters its energy and wavelength. In simple terms, when light hits molecules, its wavelength shifts slightly, leading to this change in color.
When light meets an object, it can bounce back (reflect), bend (refract), or pass through (transmit).
Scientists study how light scatters by checking if the particle it hits can change its energy. This means that when light interacts with a particle, it might gain or lose some energy, which can slightly change its wavelength or color.
Here’s a simple way to understand it:
– Light is made of tiny energy packets called photons.
– When a photon interacts with a molecule, it can either gain or lose some energy.
– This change in energy affects the wavelength of the photon:
– More energy → Shorter wavelength (moves toward blue light).
– Less energy → Longer wavelength (moves toward red light).
– However, new photons are not created or destroyed in this process—the same photon just shifts in energy.
This is how light changes color slightly when it interacts with particles, as seen in the Raman Effect.
Light Scattering and Material Analysis Explained
In their first report to Nature, titled “A New Type of Secondary Radiation,” C.V. Raman and K.S. Krishnan shared their discovery after studying 60 different liquids. They found that in every case, a small portion of the scattered light had a different color than the original light. Raman emphasized that this was a universal phenomenon that needed to be recognized.
Raman later confirmed these findings using a spectroscope and recorded the exact measurements. He published these detailed results in the Indian Journal of Physics on March 31, 1928.
A spectroscope is a scientific instrument that splits light into its different colors (spectrum) to analyze materials based on how they absorb or emit light. It helps identify elements and study light properties.
CV Raman’s discovery had a huge impact worldwide, going beyond what he initially intended. In his 1930 Nobel Prize speech, he explained that studying scattered light helps us understand the fundamental structure of the material it passes through.
During that time, scientists were deeply focused on quantum theory, which explains how tiny particles behave. Raman’s discovery was important because it helped scientists understand how light interacts with different materials at a very basic level. His work provided new insights into the nature of light and matter, making a big impact on physics.
Light and Matter: A Scientific Connection
Light is a form of energy that travels in waves and allows us to see things. It includes visible light, as well as invisible forms like X-rays and infrared.
Matter is anything that has weight and takes up space, like air, water, rocks, and even our bodies. It is made up of tiny particles called atoms.
When light interacts with matter, it can be absorbed, reflected, or scattered, sometimes changing color or direction. This interaction helps scientists learn more about materials and their properties.
Studying Materials Safely with Raman Spectroscopy
Raman’s discovery became very useful in chemistry, leading to the development of a new technique called Raman spectroscopy. This method helps scientists study different substances without damaging them. It is used to analyze both natural (organic) and artificial (inorganic) materials, making it a powerful tool for identifying and understanding chemicals.
With the development of lasers, which can produce much stronger and more focused light beams, Raman spectroscopy has become even more useful. Over time, its applications have greatly expanded, making it an important tool in many scientific fields.
Today, Raman spectroscopy is used in many different ways. It helps experts study artwork and historical objects without damaging them. It is also used at airports and border checkpoints to detect hidden drugs inside luggage.
(Girish Linganna is a Defence and Aerospace Analyst based out of Bengaluru. He is also the Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany. The views expressed in this article are of the author only.)
