Dear Editor,
I should like to communicate to you a preliminary account of some experiments on the scattering of light by liquids that have led me to what I believe to be an entirely new type of phenomenon.
In the case of every liquid so far examined, the scattered light contains modified radiations which are not present in the incident beam. The modifications consist in the appearance of new frequencies, some higher and some lower than the incident frequency, the differences being characteristic of the scattering material.
When a parallel beam of sunlight is allowed to pass through a carefully filtered liquid, and the track of light through the liquid is observed in a direction perpendicular to its path, a very feeble cone of scattered light is visible. When this scattered light is analysed with a direct vision spectroscope, it is found to contain, in addition to the original wavelength, new wavelengths on both the red and violet sides.
The phenomenon appears to be a universal one in the case of transparent media in all physical states. I have observed it in the case of sixty different liquids, including water. The effect is quite distinct from fluorescence, as it occurs even with incident light of longer wavelengths for which the substance exhibits no appreciable ordinary absorption.
The new radiations are polarized and appear immediately when the primary beam is passed through the material. The intensity ratios between the new frequencies and the original frequency remain constant for each substance but vary from one substance to another, suggesting that these shifts are characteristic molecular properties.
This discovery opens up entirely new possibilities for the study of molecular structure and the investigation of the ultimate constitution of matter. The potential applications in chemical analysis and the study of crystal structure appear to be of considerable promise.
I am continuing intensive investigations into this phenomenon and hope to publish a complete account of the experimental findings and theoretical interpretation in the near future.
I remain, Sir, Your obedient servant,
C.V. Raman
Indian Association for the Cultivation of Science Calcutta, India
About This Letter
Historical Context
This letter to Nature journal announced one of the most significant discoveries in 20th-century physics - the Raman Effect. The discovery was made on February 28, 1928, and reported to Nature on March 31, 1928, just 31 days later.
Significance
This discovery revolutionized spectroscopy and led to Raman becoming the first Asian to win the Nobel Prize in Physics in 1930. The Raman Effect has applications in chemistry, physics, and materials science that continue to this day.
About C.V. Raman
Sir Chandrasekhara Venkata Raman (1888-1970) was an Indian physicist who made groundbreaking contributions to the field of light scattering. He served as the first Indian director of the Indian Institute of Science and founded the Indian Academy of Sciences.
About Editor, Nature Journal
Nature is one of the world's most prestigious scientific journals, first published in 1869. Publishing in Nature was (and remains) one of the highest honors for a scientist, marking discoveries of fundamental importance.
Additional Resources
- C.V. Raman Nobel Prize Biography Official Nobel Prize biography and lecture
- The Raman Effect Explained Scientific explanation of the Raman Effect
- Nature Journal Archives Original publication in Nature, 1928