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Do you know who the second-fastest recipient of the Nobel Prize in Science is?

It is a matter of great pride that an Indian, Sir C. V. Raman, is credited with this enviable record. Usually, it takes anywhere from 10 to 20 years for the award selection committee to declare the winner, as it takes much time to validate the discovery/invention. Such was the importance of his discovery, famously known as the Raman effect, that it was made in February 1928, and the Nobel Prize was awarded to him in 1930, which is roughly two years and eight months. (Incidentally, the fastest winners are Georg Bednorz and Alex Müller in 1987, for their discovery of High-Temperature Superconductivity in 1986, which is less than two years.)

Life of Sir C V Raman

C V Raman holds many such high-speed records. Born on 7/11/ 1888 in Thiruchirapally, Tamil Nadu, he completed matriculation at the age of 11, a degree in physics with a Gold Medal at the age of 16 from Madras Presidency college, and post-graduation in Physics at the age of 19 with highest honors. In the same year, 1907, he topped the Indian Civil Service Examination and joined the Indian Finance Department. Due to his passion for science, he left the Civil Service and joined the University of Calcutta as the first Palit Professor of Physics in 1917. In 1929, he was knighted, and in 1930, he was awarded the Nobel Prize for his discovery, which bears his name, the Raman effect. He was the first Asian to receive the Nobel Prize in the science discipline and the fastest winner till then. In 1933, he became a professor at the Indian Institute of Science, Bangalore. Later, he served as its first Indian Director, as well. He founded the Indian Academy of Science in 1934 and, in 1948, established the Raman Research Institute. Sir Raman never accepted government funding for IAS and RRI to uphold the institution’s independence and standards. He was awarded the Bharat Ratna in 1954, which was instituted in the same year. He left this world on 21/11/1970.  

Raman and Chandra, The Indian Nobel Laureates.

In the last essay, Jataka of Stars, we discussed the Chandrasekhar limit, discovered by another Indian Nobel laureate, Subramaniam Chandrasekhar. It is fascinating to know that Raman was the maternal uncle of Chandra, as Chandra’s mother was the younger sister of Raman.

Let us look into some interesting facts about the life of the Uncle and Nephew duo.

 It is a beautiful and profound coincidence that both the uncle and the nephew made their discoveries during their rhythmic and contemplative sea voyage. One of the smallest interactions in nature (the photon-molecule exchange) was discovered by Raman, while one of the largest fates in nature (the collapse of a star) was discovered by Chandra; both were forged in the same solitary boundless environment in the background of the mighty ocean. Raman looked through the sea to find his ‘photon shift’ and Chandra gazed beyond the sea, to the stars, to contemplate his ‘limit’.  

Raman undertook his sea voyage to participate in the Congress of Colonial Universities held at Oxford in 1921. During his return voyage aboard ‘SS Narkunda’, the blue color of the vast Mediterranean ocean captured his attention. Till that time, it was attributed to the reflection of the blue sky in the water behind the reason for the blue color. This theory by Lord Rayleigh was not convincing to Raman, whose mind was already sharp with the physics of acoustics and light. He conducted his experiments on the deck using the simple equipment, the Nicol prism, which he was carrying with him. He found that scattering of light was the reason for the blue color of the Ocean. Let us look into this in detail in the latter part of the essay.

During his lifetime, Chandra was overshadowed by his uncle Raman, who won the Nobel Prize in 1930 at the age of 42, the year in which Chandra undertook his voyage aboard the vessel ‘Pilsna’ as a young scholar and introduced his theory of the Chandrasekhar limit during this voyage. The Raman effect was a discovery backed by experiments and could be validated immediately. The Chandrasekhar limit was discovered based on mathematical theories and could not be validated immediately. Chandra encountered humiliation from prominent Western scientist Eddington and some other scientists, who doubted the validity of his theory, even though not on scientific grounds, but based merely on their intuitions. Even Chandra’s own uncle, Raman, was not an enthusiast of his discovery backed by mathematical theories. All these humiliations forced Chandra to build his career in the US.

Raman Effect and Its Significance

Background.  We are all familiar with light passing through various media like air, water, and glass etc. As discussed in one of the earlier essays, light is nothing but a flow of photons in a wave form. These photons possess their own energy level, frequency, and wavelength.

When a beam of monochromatic light passes through a transparent material, most of the light passes through the medium without undergoing any change in its properties, viz., energy, frequency, or wavelength. That means the incident light and scattered light have the same properties and are called elastic scattering.  This much was known at the time of C V Raman, and this phenomenon was known as Rayleigh Scattering.

Raman’s Discovery.           Raman discovered a phenomenon called Inelastic scattering (Raman Scattering). When light interacts with matter, a small portion of scattered light changes frequency or wavelength. This phenomenon is known as the Raman Effect. This Raman scattering is happening to a very small fraction of photons only. The majority undergo Ryleigh scattering.

            Raman found that the shift in frequency of the inelastic scattered light is caused by an exchange of energy between the incident photon and the molecules of scattering material.

            Raman found that Scattered light can have a frequency higher than the frequency of the incident light or lower than that of the incident light.

When incident photons give energy to the molecules of the scattering material, the resultant scattered light has a lower frequency, and the molecules of the scattering material are excited to a higher vibrational level. The resultant lines in the spectrum are called Stokes lines.

Scattered photons gain a higher frequency when they gain energy from the molecules of the scattering medium. This happened because the molecules were already in an excited vibrational state, and they transferred their energy to the incident photons and went to a lower energy level. They are called Anti-Stokes Lines.

This specific difference in frequency of the scattered light corresponds precisely to the natural vibrational and rotational frequencies of the molecules of the scattering medium. Simply saying, on the atomic or molecular structure of the material.

Significance and Applications.   Raman found that, Raman shift happens without altering the structure and dynamics of the material (Non-Destructive). Raman shift is determined by the molecule’s chemical bond and symmetry. The Raman effect is universally observed in all states of matter and is independent of the nature of incident photons.

            The Raman effect provides a ‘fingerprint’ of the material’s molecular structure, as the shift in wavelength is unique to the vibrations and rotations of molecules within it, offering deep insights into its molecular structure. In other words, the Spectrum can be used to identify the matter. The non-destructive nature of the Raman effect allows the analysis of materials without damaging the sample. The discovery of the Raman effect provided crucial experimental evidence for the quantum nature of light.

            The practical exploitation of the Raman effect is through Raman Spectroscopy, for molecular identification, analysis of crystal structure, biological analysis of DNA, Proteins, cells, detecting biochemical changes in tissues, identifying drugs, explosives, and hazardous chemicals, and nanotechnology. A Raman spectroscope is widely used in identifying the chemical composition and crystalline structure of rocks in planetary bodies, and also to detect both organic and inorganic compounds necessary for life.

            So, what Raman discovered through his experiments on the deck of the ship and explained how the ocean gets its blue color through a natural phenomenon identified as scattering of light, turned out to be one of the most revolutionary discoveries of the twentieth century.

Despite the intellectual handicaps and primitive facilities in the British era, Raman staunchly chose to remain in India, building institutions and infrastructure. Raman challenged the ‘inferiority complex’ of the Indian Scientists that made them blindly accept foreign ideas. He famously stated that “it was better to work with the most inefficient, useless equipment of ours than to shine in the borrowed feathers”. February 28, the day on which he discovered the Raman effect, is celebrated as National Science Day in India.         

Audio Credits: Om Mani Pae Mey Hum – Buddhist Chant