CV Raman
CV Raman
Photo: Twitter

The National Science Day is celebrated every year on February 28 in India. This day marks Indian Nobel laureate, Sir CV Raman and his student, K.S. Krishnan’s discovery of the Raman Effect. This discovery gave Asia the first Nobel Prize in Physics in 1930.

It was in 1928 that the duo of Raman and Krishnan had discovered the phenomenon, but it was only two years later that Raman’s Nobel came. It was the first instance where a non-white person won a Nobel in the Sciences.

What is the Raman Effect?

Encyclopaedia Britannica defines the effect as, “A change in the wavelength of light that occurs when a light beam is deflected by molecules. When a beam of light traverses a dust-free, transparent sample of a chemical compound, a small fraction of the light emerges in directions other than that of the incident (incoming) beam.”

It further goes to state that, “Most of this scattered light is of unchanged wavelength. A small part, however, has wavelengths different from that of the incident light; its presence is a result of the Raman effect.”

Why is the phenomenon named after C.V. Raman?

In 1921, while on a trip to Europe, Raman noticed the blue colour of some icebergs and the Mediterranean Sea. This striking phenomenon made him want to understand the reason behind it. Conducting experiments with transparent blocks of ice and the light of a mercury arc lamp, recorded the change in the wavelength of light after shining the light through the ice cube. This phenomenon later came to be known as the Raman Effect.

Although he was not the first person to observe the effect, Raman became the first person to publish the observations of the effect in 1928. It was first observed just one week before Raman by Russian physicists Leonid Mandelstam and Grigory Landsberg; however, they did not publish their results until months after Raman.

Why does India celebrate the National Science Day today?

The Indian government, in 1986, declared 28th February as National Science Day to commemorate the discovery of the Raman Effect. This day is celebrated in academic and scientific institutions all over the country to spread the message of the importance of science and its application among people. This year’s theme is ‘Women in Science’.

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