Raman Effect: fingerprinting the universe

At school, we were taught that Sir CV Raman won the 1930 Nobel Prize for Physics for discovering the “Raman effect”. But when we asked what exactly the Raman Effect was, our science teacher fobbed us off, saying “it’s very complicated.” Clearly, even he didn’t know. Cynical students wondered why a complicated discovery without any obvious use had won the Nobel Prize.

But today, Raman’s discovery has finally become a breakthrough technology. Hand-held scanners called Raman scanners, weighing just one-third of a kilo, are being used by US narcotics squads and airports to detect drugs. Security experts think that Raman scanners may be the best devices to detect explosives carried by terrorists. Safety inspectors are using Raman scanners to detect hazardous chemicals and gases. Police forces are using Raman scanners for forensic work.

The scanners work by detecting the molecular structure of the object they are scanning. If you shoot a beam of light on an object, a very small part of it interacts with the atoms of the object and scatters light in a pattern or spectrum unique to that particular molecule. This is the Raman Effect. It is difficult to detect, and typically needs lasers to amplify the signal. Every molecule has a different Raman pattern. This is why Raman scanning has been called the fingerprinting of the universe: it can identify substances as surely as fingerprints can identify humans.

Identifying the chemical composition of a substance typically requires chemical and physical tests that take time, maybe days. They typically require a sample to be extracted and destroyed while testing. But Raman scanning can take just 20 seconds. It does not require cutting, extracting or destroying a substance. Scanners have a laser, spectroscope and an electronic heart that can recognize Raman patterns. This yields almost instant recognition of target substances.

For instance, narcotics squads in the US are using Raman scanners programmed to detect up to 100 drugs. At the scene of a crime, or during airport security checks, the scanner can tell whether a substance is heroin, crack cocaine, amphetamine, or plain chalk. Security experts can programme scanners to detect different sorts of explosives such as RDX or nitroglycerine.

For decades, Raman’s discovery could not be converted into easily usable or affordable tools. In his time, equipment for lasers and spectrum separation and scanning were primitive, bulky and costly. Only in the 1980s did laser technology progress to the point where it was compact and economic. This new technology was most popularly established in the CD player: a laser could scan a disc to play music.

Scientists in many fields, including space and telecom, began to research applications for the Raman Effect. Some found ways to enhance the Raman Effect by adding surface metals, making the effect easier to detect. This led ultimately to the invention of scanners that could detect trace elements of less than one part per billion. Such scanners can identify minute quantities of bacteria, chemical pollutants, or explosive elements.

A recent article in The Atlantic, a US monthly, says that Raman scanners are gradually becoming big business. It cites officials at Delta Nu, a manufacturer of Raman scanners, as saying that scanners are already a $150 million business, and growing fast. The company’s scanners currently cost $15,000 each, but it hopes to cut the cost to just $5,000 in the next five to ten years.

Researchers at UCLA and Intel have incorporated the Raman Effect on silicon. Because of its crystalline structure, the Raman Effect is 10,000 times stronger in silicon than glass. Researchers at JPL and Caltech have found other ways to increase laser efficiency. This has driven down size and costs.

Researchers at Stanford University are experimenting with Raman scanners to diagnose cancers in various organs. River Diagnostics in Rotterdam is marketing a bacteria analyzer that hospitals can use to instantly detect deadly pathogens. One day, Raman scanners may make blood tests obsolete: a scan may suffice to tell you the content of glucose, cholesterol, uric acid and other elements in your blood.

Scientists aim ultimately to create a database of Raman patterns of every substance for easy identification. This is similar to Nandan Nilekani creating a national database for fingerprints and irises to identify every Indian. Databases have already been created for narcotics, pollutants and explosives, which is why scanners have already become practical tools.  Every time they are used to catch a drug smuggler or terrorist, or to detect a cancer or pollutant, we can give thanks to CV Raman. School teachers can now teach students why exactly the Raman Effect is so important: it fingerprints the universe.

11 thoughts on “Raman Effect: fingerprinting the universe

  • 2014.Feb.19 at 14:43
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    Explanation given here is in very simple language. Other details mentioned in article are very involving & elaborate. This article will surely arouse interest in any general person to read articles related to science & technology. Good work of Science communication in real sense.

    Thanks a lot Sir!

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  • 2012.May.19 at 00:49
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    your articles change the paradigm, from just being on looker in many debates, I’m just participating in those with my friends, and praises: sum of all the above and you hit the nail head on. GUTSY. I LOVE THAT CHARACTER IN YOU, which in turn is helping people like me. thanks again

    Reply
  • 2010.Oct.07 at 15:02
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    I have little know how of raman effect, but did’t know it application that well, this article has further deepen my respect for SIR CV RAMAN. thanks very much

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  • 2010.Jun.28 at 17:21
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    I wish every School in India had a teacher like Mr. Swaminathan. His simple and lucid explanation, be it Economics or Science, would go a long way in helping the students to love their subjects especially Science and Math.

    Thanks a lot Sir!

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  • 2010.Jun.24 at 12:55
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    hey very informative…

    Reply
  • 2010.May.20 at 17:17
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    We should really feel proud as an Indian to have an aborigine scientist who discovered the Raman Effect. It was certainly a mystery in our childhoods but that discovery in the 1920s emerged as a boon to the modern day science.

    Its pragmatic implementation is certainly able to battle such nefarious issues such as smuggling and terrorism. In addition of these features, it bolstered the revolution in medical science too. I highly appreciate the author’s view about the Raman Effect in referring it as “Fingerprints of the universe.”
    Now, its high time when the scientist from all over the world should consider such discoveries for more such implementations including new innovations in medical science which could lead to a healthier and safer planet in the coming future.

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  • 2010.May.18 at 19:27
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    good day sir !
    I am and have always been a big fan of your writings . Your careful analysis of a range of problems , policies and events have been the most thought provoking in a very positive sense .
    Your outlook , knowledge and simplicity which is reflected in your writings are an inspiration to me and i hope i can stay unbiased and focused like you in whatever life brings to me .
    On a personal level your writings have helped me a lot in doing good in debates and group discussions .
    thank you ! and good luck for the future .
    ps: the new look for the site is great .

    Reply
  • 2010.May.15 at 23:49
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    I guess I identified myself more with the teacher at Mr. Ayiyar’s school. The reason being that even I thought that any concept that deserves a nobel would be complicated enough for normal people to not to understand.But Mr Ayiyar has exlained it in such a lucid language that I was not only able to understand the concept in clear series but could also see the images of the explanations happening in my mind. This can be the work of a real veteran in his field.And Mr Swaminathan is no doubt a one.
    but I thought him to be the master of the field of economics. He is adept at the issues concerning science too was no less than a revelation……and quite a happy revelation!!

    Reply
  • 2010.May.15 at 20:27
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    mr. swminathans articles be they on economy or even science or other topics open the floodgates of understanding of these in a clear and cmprehensive way.

    Reply
  • 2010.May.10 at 19:26
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    Yes, Raman Effect is one of the most important research done by an Indian. The uses as rightly pointed by the columnist are immense in narcotics, pollutants and health industry. If MBA was pronounced those days and the scientists knew about how to commercialise and patent the use of such technologies, we would have seen more industrialists-scientists from India/ Indian origin.
    Indeed a great article!.

    Reply
  • 2010.May.10 at 17:01
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    Hello Sir,

    didn’t expect something scientific from you….But you rocked!! a great writeup….You explained science as easily as you explain economics…Hats off to you!!

    Reply

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