The Gist of Science Reporter: February 2014
ICON OF INDIAN SCIENCE
The significance of the Raman Effect was recognized quickly
by scientists all over the world. Professor RW. Wood of Johns Hopkins cabled
Nature to report that he had verified Raman’s “brilliant and surprising
discovery” in detail. He declared that this discovery which resulted from
Raman’s long and patient study of the phenomenon of light scattering is one of
the most convincing proofs of the quantum theory.
When people made comparisons to the well known Compton
effect, Raman prophetically stated that his effect which involved molecular
scattering would have greater implications than the Compton scattering, which
had to dowith electron scattering of photon.
Raman also recognized that his discovery was important to
firmly establish the new quantum theory; because an explanation of the new
radiation required the use of photons and their change in energy as they
interacted with the atoms in a particular molecule. Raman also knew that there
was a more important result, remarking in his 1930 Nobel Prize address that “
... the character of the scattered radiations enables us to obtain an insight
into the ultimate structure of the scattering substance.”
By the late 1930s, the Raman Effect became an important
method of nondestructive chemical analysis for both organic and inorganic
compounds. The unique spectrum of Raman scattered light for any particular
substance served as a “fingerprint” that could be used for qualitative analysis,
even in a mixture of materials. Further, the intensity of the spectral lines was
related to the amount of the substance. Raman spectroscopy could be applied not
only to liquids but also to gases and solids. And unlike many other analytical
methods, it could be applied easily to the analysis of aqueous solutions. It was
a ubiquitous technique, giving information on what and how much was present in a
wide variety of samples.
The use of Raman spectroscopy as a basic analytical tool
changed sharply after World War II. During the War, infrared spectroscopy was
enhanced by the development of sensitive detectors and advances in electronics.
Infrared measurements quickly became routine operations, while Raman
measurements still required skilled operators and darkroom facilities. Raman
spectroscopy was sidelined for a while because of Infrared spectroscopy. But
with the advent of another great discovery in the 1960s, that of laser, interest
in Raman spectroscopy was again revived. Now it finds application in many
diverse fields like medical imaging and Biochemistry.
He was knighted by the British government in India and received the Nobel
Prize in physics in 1930 (among all the Nobel Prizes awarded, this must have
been the shortest in duration from the time of discovery).
Three years later, Raman left Calcutta for Bangalore, where
he was posted as the Director of the Indian Institute of Science (the first
Indian to hold the post which was dominated by the British; his knighthood must
have made it possible). There he continued his work on the Raman Effect and
became interested in the structure of crystals, especially diamond.
In 1934, he founded the Indian Academy of Science and began the publication
of its Proceedings.