National Science Day: 96 Years Ago, Sir CV Raman Changed How Indian Science Was Perceived

National Science Day 2024: India celebrates National Science Day on February 28 every year to mark the contributions of scientists towards the development of the country. On this day, in 1928, Indian Physicist Sir CV Raman made an important discovery in the field of spectroscopy, which was later named after him - the Raman Effect.

Mr. Raman received the Nobel Prize in Science in 1930 for his outstanding discovery. On this occasion, schools, colleges, universities, and various academic, scientific, technical, medical, and research institutions organise quiz competitions, seminars, and other events.

What is the Raman Effect?

The Raman effect, also known as Raman scattering, is a phenomenon where light interacts with molecules and changes its wavelength. This interaction is different from the typical scattering of light, as it involves an exchange of energy between the light and the molecules.

Here's a quick summary of the points you mentioned:

Spectroscopy: The website rightly connects the Raman effect to the field of spectroscopy, which deals with the interaction of light with matter.

Scattering of Photons: You accurately stated that the Raman effect involves the scattering of photons (particles of light) by molecules.

Change in Wavelength: The core principle of the Raman effect, the change in wavelength of the scattered light, is clearly explained.

Molecule Excitation: While the website mentions "excited molecules at higher energy levels," it's important to note that not all Raman scattering involves an initial excited state of the molecule.

Intensity of Scattered Light: You accurately mentioned that only a small portion of the scattered light exhibits a change in wavelength due to the Raman effect.

Who Was CV Raman?

CV Raman was born in Tiruchirapalli in Tamil Nadu in 1888. He was a bright student with a huge interest in science, especially in the field of sound and light. The vibrations of sound and light fascinated him and that's what he did his research on at the Indian Association for the Cultivation of Science. It wasn't long before Raman's work started getting published in famous journals and he became the toast of the Indian scientific community.

His seminal work on the Raman Effect only began when at the age of 27, he was offered professorship of physics at Calcutta University.

While returning from London to Bombay, in 1921, Sir CV Raman was fascinated with the deep blue color of the Mediterranean Sea. Unable to accept a British scientist Lord Rayleigh's theory that the sea just reflected the colour of the sky, Raman came up with a different theory as to why the water molecules also scattered light particles, and not just reflected them.

Just a year or so later, Raman was able to conclusively prove that the colour of the sea was a certain type due to the scattering of sunlight by water molecules. This discovery shook the scientific world at the time.

The Raman Effect essentially was all about accurately predicting and measuring the change of wavelength of light particles as it scattered while travelling through a medium (water, glass, other liquids, etc.). Doing this wasn't easy at the time, as the Raman Effect is very weak -- only one in a million of the scattered light particles, or photons, actually exhibits the change in wavelength that any observer is looking for. That's why no one could find it -- it was painstakingly difficult.

It took CV Raman and K.S. Krishnan, his partner in crime, to study light travelling through 60 different liquid types to conclusively say that the light that went into these liquids didn't come out exactly as its original form. There was some scattering of light particles every single time, which Raman called as "A New Type Of Secondary Radiation" in his report to Nature, which later on came to be referred as the Raman Effect.

Legacy of Raman Effect

Sir CV Raman was able to discover a whole new behaviour of light which great minds at the time thought didn't exist, and was therefore able to open a whole new world of scientific discovery and applications of the phenomenon of light.

Not just in the field of physics, whether it validated the quantum theory of particles, but also in chemistry with determining the nature of any particle through spectroscopic analysis, the Raman Effect played a crucial role in widening humanity's understanding of the behaviour of light.

No wonder India celebrates this day, when Sir CV Raman published his seminal Raman Effect theory, as National Science Day, in recognition of a true scientific genius and one of the most gifted minds of the 20th century.

Header Image: Thefederal.com

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