remembering Kariyamanikkam Krishnan, co-discoverer of Raman scattering !!

On this day, 95 years ago, the great Physicist Sir CV Raman   discovered what is now known as Raman scattering, for which he later became the first Asian to win the Nobel Prize in Physics.  .. .. honestly, I understand nothing of this pic and have not heard of this great personality earlier (not CV Raman !!)

Sir Chandrasekhara Venkata Raman FRS (7.11.1988 to 21.11.1970) was  a physicist known for his work in the field of light scattering. Using a spectrograph that he developed, he and his student K. S. Krishnan discovered that when light traverses a transparent material, the deflected light changes its wavelength and frequency. This phenomenon, a hitherto unknown type of scattering of light, which they called "modified scattering" was subsequently termed the Raman effect or Raman scattering.  Sir Raman received the 1930 Nobel Prize in Physics for the discovery and was the first Asian to receive a Nobel Prize in any branch of science.

Raman scattering or the Raman effect is the inelastic scattering of photons by matter, meaning that there is both an exchange of energy and a change in the light's direction. Typically this effect involves vibrational energy being gained by a molecule as incident photons from a visible laser are shifted to lower energy. This is called normal Stokes Raman scattering. The effect is exploited by chemists and physicists to gain information about materials for a variety of purposes by performing various forms of Raman spectroscopy.

Light has a certain probability of being scattered by a material. When photons are scattered, most of them are elastically scattered, such that the scattered photons have the same energy (frequency, wavelength and color) as the incident photons but different direction.  

The Raman effect is named after the great  Indian scientist C. V. Raman, who discovered it in 1928 with assistance from his student K. S. Krishnan. Raman was awarded the 1930 Nobel Prize in Physics for his discovery of Raman scattering. The effect had been predicted theoretically by Adolf Smekal in 1923.

For sure we read about Sir CV Raman in school text books but did we about Sir Kariamanikkam Srinivasa Krishnan who too was born in a Vaishnavaite family in Watrap, Tamil nadu.

KS Krishnan (4.12.1898 – 14.6.1961) was a great Physicis who was  co-discoverer of Raman scattering, for which his mentor C. V. Raman was awarded the 1930 Nobel Prize in Physics. His father was a farmer-scholar deeply versed in Tamil literature. He had his early education in Hindu Higher Secondary school, in Watrap, after which he attended the American College in Madurai and the Madras Christian College. After gaining his degree in Physics he became a demonstrator in chemistry.

In 1920, Krishnan went to work with C.V. Raman at the Indian Association for the Cultivation of Science, Calcutta. There he engaged himself in experimental study of the scattering of light in a large number of liquids and its theoretical interpretations. He played a significant role in the discovery of the Raman scattering. In 1928 he moved to the Dacca University (now in Bangladesh) as the Reader in the physics department where he studied magnetic properties of crystals in relation to their structure. Krishnan, along with other rising scientists such as Santilal Banerjee, B.C. Guha, and Asutosh Mukherjee developed an elegant and precise experimental technique to measure the magnetic anisotropy of diamagnetic and paramagnetic crystals. Their findings were published by the Royal Society of London in 1933 under the title, Investigations on Magne-Crystallic Action.

In 1933 he returned to Kolkata to take up the post of Mahendralal Sircar Professor of Physics in the Indian Association for the Cultivation of Science where he continued to collaborate fruitfully with Banerjee to elaborate on the magnetic properties of crystals in relation to their structure.  Krishnan was elected as Fellow of the Royal Society (FRS) in 1940.

His Royal Society candidature certificate in 1935 read: "Distinguished for his investigations in molecular optics and in magne-crystalline action:collaborated with Sir C.V. Raman in extensive theoretical and experimental studies on light scattering, molecular optics and in the discovery of the Raman Effect (1928). More recently has been publishing many valuable investigations (Phil Trans Royal Society and elsewhere) on the significance of magnetic anisotropy in relation to crystal architecture and thermo-magnetic behaviour at the lowest temperatures. Has published important work on pleochroism in crystals and its relation to photo-dissociation. Leader of an active school of research in Calcutta.

In 1942, he moved to Allahabad University as Professor and Head of the Department of Physics where he took up the physics of solids, in particular of metals. He was knighted in the 1946 Birthday Honours List and awarded the Padma Bhushan by the Government of India in 1954. He was the first recipient of the prestigious Bhatnagar Award in 1958. On 4 January 1947 K. S. Krishnan was appointed first director of National Physical Laboratory India. This was one of the earliest national laboratories set up under the Council of Scientific and Industrial Research.

Inspirational !  - should we not be reading the life history of such great people instead of Babar, Aurangazeb, slave dynasty, Robert Clive Clement Atlee .. .. .. and you know who !!

With regards – S. Sampathkumar
28.2.2023