Why is the sea blue? A question, a Nobel Prize and the birth of a global industry…

July 2, 2020

 

“A voyage to Europe in the summer of 1921 gave me the first opportunity of observing the wonderful blue opalescence of the Mediterranean Sea.”-   Prof. C V Raman, Nobel Prize in Physics, 1930 (the first non-white, Indian or Asian to receive a Nobel Prize in any branch of Science)

 

This story begins with a voyage undertaken by C V Raman to the UK in the summer of 1921. Observing the Mediterranean while on board the ship, Raman wondered why the sea was so blue. The initial answer seemed to be that it was due to the scattering of light by water molecules, same as the explanation provided by Lord Rayleigh for why the sky is blue.  

 

To test this explanation, Raman started experiments with his scientific collaborators and students at the Indian Association for the Cultivation of Science (IACS), Calcutta upon his return to India in September 1921. It soon became evident to them that the question was a fundamental scientific problem, and that the molecular scattering of light was a very general phenomenon which could be studied in gases and vapours, as also in liquids and solids.

 

For the next seven years, Raman and his associates continued to research this question, with many improvements to their scientific apparatus and techniques as they learnt more and more about the subject. In February 1928, Raman announced his findings to the press and sent his experimental data to Nature, where it was published in May 1928.  The ‘Raman effect’ as it soon came to be called, was not only a phenomenon in itself, but one of the earliest proofs of the quantum nature of light. By 1929, the Raman effect was independently verified by other researchers, and in 1930 the Nobel followed. 

 

What is the Raman effect?

 

 

The Raman effect is the inelastic scattering of light by matter, meaning there is an exchange of energy between a photon of light and a molecule that it strikes. The molecule either gains (usually) or loses energy, so the scattered light has an energy different (usually lower) from the incident light. This changes the frequency and therefore the colour of the scattered light. The change of colour can act as an ‘optical fingerprint’ for the molecule.

 

Why does all this matter?

 

This discovery of an optical fingerprint of a material forms the core intellectual property for the field of Raman spectroscopy, which is a non-destructive, in situ method to analyse materials and live tissue. It has many applications that directly and indirectly improve the quality of our lives, including:

  • Chemistry - to identify molecules and study chemical bonding and intramolecular bonds.

  • Solid-state physics - to characterise materials and measure temperature.

  • Biology and medicine – for tissue imaging, wounds characterization and many other uses. 

  • Bio-pharmaceuticals – to identify active pharmaceutical ingredients (APIs) and their polymorphic forms, if any. 

  • Investigation of art and heritage works. 

 

 

 

Almost 100 years after the original research, Raman spectroscopy remains a vibrant area. Over the years, over 25 variants of Raman spectroscopy have been developed, with new applications being found all the time. The global market for Raman spectroscopy is estimated to be $1.8 billion in 2021, with numerous companies all over the world making a range of products for the above applications.

 

The original research and intellectual property have been continuously expanded and improved upon by generations of researchers, engineers and entrepreneurs to create an entire industry. And it all began with one man’s curiosity about why the sea is blue. 

 

In my upcoming course, Products, IP and Entrepreneurship, we will be exploring this journey of an idea, through its many stages of nurturing and support, the many challenges it faces along the way, to its final destination as a product and maybe an industry. 

 

References

1. https://www.nobelprize.org/nobel_prizes/physics/laureates/1930/raman-facts.html

2. https://www.famousscientists.org/c-v-raman/

 

Read more about the author of this post, Kiran HR, here.

 

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