Introduction:
“Science is not only a disciple of reason but, also, one of romance and passion” – Stephen Hawking. This very statement can be read as a statement by any educated soul but can be soul-felt only by fortunate people. And Dr. KS Krishnan (Dr.Kariamanikkam Srinivasa Krishnan) is one among them. His contributions to physics are in diverse fields. He has taken the role of a research scholar, reader of physics, professor, head of the department and so on in his career. He always told his students, “Physics means facing facts”.
Collaboration with Dr. CV Raman:
Dr. KS Krishnan was promptly given a research assistantship by Dr. CV Raman when he attended classes at the University College of Science. The laboratories in the University College of Science were just being set up and were not fully equipped at that time. Because of this, the students of the college had to often brainstorm and set up experiments on their own. This conferred them initial exposure to the experimental Physics and helped them to develop appreciable skill set of working with hand creating an excellent ambience for learning physics. This became a great advantage to Dr. KS Krishnan. He learned the different branches of Physics thoroughly before becoming a member of Raman’s research team. He trained himself in mathematics, seeking help from the Mathematics Faculty at the University. In November 1923, Dr. KS Krishnan officially joined Indian Association for the cultivation for science (IACS) as a research scholar to work under Raman’s supervision. Afterwards, he spent five years at the Association under the close guidance of Raman.
He started investigating the scattering properties of 65 dust-free liquids and its theoretical interpretations. He conducted extensive experiments in the summer of 1924 and concluded that a feeble fluorescence was evinced by several liquids and that the selected blue region of the incident white light beams excited fluorescence in the green. His first scientific paper with the above-mentioned results was published in 1925 in Philosophical Magazine under the title “On the molecular scattering of light in liquids”. Raman was deeply impressed by his sovereign, creative and authentic research capabilities.
The Raman effect:
It was during 1926 and 1927 that Dr. KS Krishnan’s collaboration with Dr. CV Raman really blossomed. The problems they worked on during this time included classical optics, electro- and magneto-optics, light scattering in fluids, flow birefringence, the Maxwell effect in liquids, etc. Dr. CV Raman’s administrative and teaching engagements made it difficult for him to dedicate time in his laboratory at the Association. In such moments, Dr. KS Krishnan undertook the natural role of leader. He also worked as an associate with Dr. CV Raman and together they published in Nature, “Optical analogue of the Compton effect” on May 5,1928. They assumed the X-ray scattering of the ‘unmodified’ type observed by Prof. Compton corresponding to the normal or average state of the atoms and molecules, while the ‘modified’ scattering of altered wave-length corresponding to their fluctuations from that state. From which they expected the same in the case of ordinary light which yields two types of scattering, one determined by the normal optical properties of the atoms or molecules, and another representing the effect of their fluctuations from their normal state. Through experiments they also confirmed that in every case in which light is scattered by the molecules in dust-free liquids or gases, the diffused radiation of the ordinary kind, having the same wave-length as the incident beam, which is accompanied by a modified scattered radiation of degraded frequency.
He was one among the thirteen scholars who worked with Dr. CV Raman at the time of discovery of Raman effect and played a significant role in it. When a controversy aroused on who deserves the Nobel prize for the Raman effect, Dr. KS Krishnan humbly called it a blatant misinterpretation. In the time and space, where people fought to claim their recognition for their contributions, Dr. KS Krishnan remained as a ‘Man of simplicity’. He never expressed his sense of disappointment at being left out, no matter what his inner feelings were. His relationship with Raman remained as cordial as before. However, in one of the written testimonials, Dr C V Raman shows how important the contribution of Dr. KS Krishnan was in getting the Noble Laureate.
On 4th October 1928, Professor Arnold Sommerfeld arrived in Calcutta gave seven lectures on “Modern developments in wave mechanics”, of which Dr. KS Krishnan took down notes. He independently worked on the intermediate mathematical steps for making the lectures clear and coherent. Sommerfeld was impressed by his ingenuity and scholarship and applauded his classic mathematical proofs.
Research at Dhaka University:
By 1931, Dr. KS Krishnan was recruited to Dhaka where he turned his attention to study the physics behind the para and diamagnetism. He developed exquisite and precise experimental techniques to measure the magnetic anisotropy of dia- and paramagnetic crystals. He was able to correlate the anisotropy of crystals with the anisotropy and arrangement of individual molecules or ionic groups. He along with his students were able to determine the orientation of molecules in the unit cell from magne-crystallic measurements. His research team developed methods for the accurate measurement of feeble susceptibilities and anisotropies. He invented a method based on the instability of the crystal when the crystal is twisted too far from the orientation, in which its strongest principal axis lies along the field. In this period, his research group published papers in renowned international and national journals. His papers on magne-crystallic phenomenon brought him appreciation all around the world. He built a research school on crystal magnetism in Dhaka, and his students were his main collaborators. In 1931, He was approved a permanent position in Dhaka University. In 1933, he submitted his doctoral dissertation to the Madras University; the thesis titled “Magnetic susceptibilities of crystals in relation to crystal structure” was submitted supplicating for the DSc degree. His examiners were impressed with his doctoral research and Nobel Laureate Physicist W. H. Bragg wrote a review on the same.
Research at IASC Calcutta:
After receiving the DSc degree, IACS in Calcutta offered him the post of the Mahendra Lal Sircar (MLS) Research Professorship.He joined IACS as the first MLS Professor on 21st December 1933. He moved to Calcutta, where he had the opportunity of working with Dr S.N. Bose. Dr S N Bose called it a good experience working with him and his students. He also collaborated with Dr. Santilal Banerjee to elaborate on the magnetic properties of crystals in relation to their structure. Their joint papers and communications (published in Nature, Terrestrial Magnetism and Atmospheric Electricity, and by the Royal Society), remain to this day, aside from a number of other pathbreaking contributions they also published in various Physics journals, the most definitive scientific studies on the structure and tendencies of small crystals. Their experiments in Dhaka and continued collaborative research in Kolkata led to what is now known as the Krishnan Banerjee method in measuring the magnetic susceptibility of small crystals.
International recognition to Dr. KS Krishnan’s work:
Dr. KS Krishnan’s works on paramagnetism in salts and diamagnetism in graphite brought him many international connections. He, along with other rising scientists such as Santilal (S.) Banerjee, B.C. Guha, and Asutosh Mookerjie 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. He was invited by Lord Rutherford to the Cavendish Laboratory, Cambridge, and by Sir William Bragg to the Royal Institution, London, to deliver courses of the lecture. In Cambridge, his initial two lectures were on diamagnetism and paramagnetism in crystals. The third lecture was about absorption and fluorescent spectra of certain aromatic compounds. After delivering lectures in Cambridge, he moved to London to deliver three public lectures at the Royal Institution. The title of his talk was “Some aspects of crystal Physics”. His work on the anisotropic susceptibility of graphite provided the concrete evidence of the validity of the quantum-mechanically based electron theory of metals. His work on graphite laid the founding stone for the field of the electronic structure of graphite. Dr. C V Raman being a fellow of the Royal society nominated Dr. KS Krishnan and in the year 1940, he was elected as ‘The Fellow of the Royal Society’ which is great honour for every scientist.
Research at Allahabad university:
His popularity grew in India after receiving the acclamation from scientific community in the west. Later joined the professorship at Allahabad University at the request of the famous palaeobotanist Prof. Birbal Sahni, where he took up the physics of solids, in particular of metals. He arrived at Allahabad University in 1942. He was an excellent teacher and taught subjects with passion. Because of his finest notoriety in teaching and research, Allahabad University started drawing bright young students. During his tenure at Allahabad University, he wrote two research papers on pure mathematical problems. The first paper titled “A Simple Result in Quadrature” was published in Nature. It dealt with the summation of certain infinite series with special properties. The second paper titled “On the equivalence of certain infinite series and the corresponding integral” was published inthe Journal of Indian Mathematical Society.
The other areas of reaseach:
In 1960, Ziman published his erudite work on the electrical properties of liquid metals and in his review, he acknowledged the inaugural work done by Bhatia and Dr. KS Krishnan. The theory of the electrical resistivity of liquid metals is now called the Bhatia-Krishnan-Ziman Theory. He was in very core group of scientists along with Homi Bhabha and S. S. Bhatnagar. In 1947, Jawaharlal Nehru requested him to assist him in Delhi as a scientific administrator. He took the charge as the first director of the National Physical Laboratory (NPL) in Delhi. While working in Delhi, he identified two new areas of research: Lattice oscillations in ionic crystals and thermionic properties of metals and semiconductors. Realizing the time crunch, he took a new PhD student S. C. Jain and appointed one of his students S. K. Roy as a Teaching Assistant at NPL. With Roy, Dr. KS Krishnan published papers on lattice dynamics and polarization fields in crystals whereas with Jain, he co-authored research papers on thermionics.
Dr. KS Krishnan as a person
He was very polite, humorous, witty and composed person. Through his sheer hard work, he won significant awards and honors. 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. He was also a fellow of numerous national and international scientific academies. He was also a philosopher and a great scholar of Tamil and Sanskrit. He was fascinated by the biographies of famous scientists like Lord Kelvin, Hermann von Helmholtz, Lord Rayleigh, J. C. Maxwell and Peter Tait. The scientific writings of Lord Rayleigh, Albert Einstein and Niels Bohr had a philosophical influence on his life. During his early college days in Madras. He was inspired by Srinivasa Ramanujan, Dr. CV Raman and had a great admiration for Dr.S. N. Bose as a giant theoretical physicist.
Conclusion:
In his research career, Dr. KS Krishnan published 135 papers out of which 50 papers were in spectroscopy, 60 papers were in magnetism, 23 papers were in thermionics and two papers of ‘Popular’ nature. He embraced his passion for physics till the very moment before his death. His last paper was finalized on the day of his death and came out a month after his death. He definitely is a role model for the current generation to emulate.
Refrences:
https://www.beaninspirer.com/kariamanickam-srinivasa-krishnan-earth-genius-co-discoverer-raman-effect/