Raman, Sir Chandrasekhara Venkata

Category: Scientist

 

Sir Chandrasekhara Venkata Raman (7 November 1888 – 21 November 1970) was an Indian physicist, who carried out ground-breaking work in the field of light scattering, which earned him the 1930 Nobel Prize for Physics. In 1954, India honoured him with its highest civilian award, the Bharat Ratna.

When ‘light’ meets particles, for example the molecules in a gas or crystal, the ‘light’ is apparently scattered - spreads in different directions. In 1928, Professor Raman discovered that a portion of the scattered light acquires other wavelengths than that of the original light. The German scientist Peter Pringsheim was the first to reproduce Professor Raman's results successfully and he called this the "Raman effect" and the spectrum the  "Raman lines."  This discovery has had enormous positive repercussions and the findings are now used, among other things, to analyse different types of material in order to identify them, of which more shortly.

the Bharat Ratna

Professor Raman was elected a Fellow of the Royal Society early in his career (1924) and knighted in 1929. He was associated with the Royal Society for 45 years although he resigned in 1968, two years before he died.

In 1941, he was awarded the Franklin Medal and in 1957, the Lenin Peace Prize.   Professor Raman was also awarded a large number of honorary doctorates and memberships of scientific societies.

 India celebrates National Science Day on 28 February of every year to commemorate the discovery of the Raman effect in 1928.

Achievements

 

In 1907, Venkata Raman came to Calcutta and in the following ten years, and in his spare time, did research at the Indian Association for the Cultivation of Science.  Some of Raman's early papers appeared as Bulletins of the Indian Association for the Cultivation of Science.  It was only in 1917 that he was offered Professorship at the University of Calcutta. 

Light, sound and diffraction

From 1917 until the end of 1921, the year of his nomination to the Fellowship of the Royal Society, his fields of research were musical acoustics and optics.  He was nominated for over 50 papers that he wrote in this time, the chief of which were

• Experimental investigations on the maintenance of vibration
• The dynamical theory of bowed strings
• Vibrations of bowed strings and of musical instruments of the violin family
• On Kaufman’s theory of the pianoforte hammer
• On the photographic study of impact at minimal velocities
• On Hertz’s theory of impact
• Photometric measurement of the obliquity factor of diffraction
• The curvature of lines in diffraction spectra
• Colours of the striae in Mica
• The diffraction figures due to an elliptic aperture and
• The colours of mixed plates

One can see that the pervading themes of this research were light, sound, vibrations, and diffraction/scattering in its various forms. 

 

In 1922, he published his work on the "Molecular Diffraction of Light", the first of a series of investigations with his collaborators which ultimately led to his discovery, on the 28th of February, 1928, of the radiation effect which bears his name ("A new radiation", Indian J. Phys., 2 (1928) 387), and which gained him the 1930 Nobel Prize in Physics.

Other investigations carried out by Professor Raman were: his experimental and theoretical studies on the diffraction of light by acoustic waves of ultrasonic and hypersonic frequencies (published 1934-1942), and those on the effects produced by X-rays on infrared vibrations in crystals exposed to ordinary light. In 1948, Professor Raman, through studying the spectroscopic behaviour of crystals, approached in a new way the fundamental problems of crystal dynamics. His laboratory studied the structure and properties of diamond, and the structure and optical behaviour of numerous iridescent substances (labradorite, pearly felspar, agate, opal, and pearls).  Among his other interests were the optics of colloids, electrical and magnetic anisotropy, and the physiology of human vision.

It is worth noting, that Professor Raman did not abandon his interest in acoustics.  There is a wonderful paper entitled On Whispering Galleries written for the Bulletin of Indian Assoc. Cultiv. Sci 7 in 1922 which explores the acoustics of the Gol Gumbaz at Bijapur, the Granary at Bankipore in Patna and the Whispering Gallery at the Calcutta GPO.  He also contributed an article on the theory of musical instruments to the 8th Volume of the Handbuch der Physik, in 1928.

The extraordinary importance of the Raman effect

It is really only now in the 21^st century that the discoveries of Professor Raman are being exploited to the full and their implications understood.  The following article is quite a good summary of some of the uses.

Raman Effect: fingerprinting the universe -  S A Aiyar, ET Bureau | May 09, 2010

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.

Mobile Raman Spectroscopy for Non-invasive Analysis of Food

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.

'A handheld device that resembles a laser pointer could
someday help doctors identify the pathogen [toxin,
bacteria, virus, heavy metal, parasite, or fungus] causing
diseases such as tumours and cancer, Alzheimers and
Dementia,  Parkinson's or Schizophrenia and Manic
depression'

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.

Thus the findings – apparently simple - of Professor Raman may revolutionise healthcare so that we can move from symptom based medicine to cause based medicine – and that indeed would be a major breakthrough.

Understanding the Raman effect in context

In order to explain how the Raman effect works, it may be helpful to summarise the findings we have made for the site by looking at the work of scientists like John Dalton, Mikhail Vasilyevich Lomonosov and Professor John Wheeler, [amongst many others].  Remember that the key sentence is that Professor Raman discovered that every molecule [atom or aggregate] has a different Raman ‘pattern’, a signature set of emissions.

The universe consists of Atoms in a sea of Energy that are held together by the forces of repulsion and attraction in the form of a lattice or matrix.

Whenever an aggregate is formed the bonds between the atoms are arranged to ensure stronger attractive forces between the atoms in the aggregate than repulsive forces.  In essence, all atoms are suspended in a 3D web like structure whose silken threads are immaterial – forces only.  For example each thing or person aggregate is 'held' to the aggregate of the earth by a force of attraction greater than the force of repulsion [and we call it 'gravity'].

 

Professor Wheeler found that the type of atoms [hydrogen, oxygen, carbon etc], their number and the exact configuration of the atoms [with their forces] within the aggregate was key to defining the aggregate.  The very definition of an aggregate  – depended on atom type, atom number, the type of forces with which it was held and aggregate shape.   And each aggregate type could have different properties.  In other words the reason some ice appears blue and some green is because although we call it ice, it is in fact many types of aggregate – different crystalline structures. And this is why very very densely packed [high attractive forces] ice is very dark green, whereas ice that is still almost snow [loosely packed, lower attractive forces] appears bluer and on to white.

This is where the Raman effect comes in.  Every crystalline structure has a fingerprint and it is not ‘light’ as such that defines the fingerprint, but the messages being received from the crystal broadcasting its properties – some of which are properties we can see – blueness or greenness.

 

Neither Atoms or Aggregates are ‘physical’.  They are analogously like software constructs, whose functions are arranged concentrically in layers around a central core.  The functions are ‘programmed’ via a unit of energy and the unit of energy is expressing via spinning.  If the unit of energy is non zero [spinning], the function is active for that aggregate or Atom.  If the unit of energy is  zero [not spinning] then the function is not expressed.  The rate of spin determines intensity – and there appear to be two directions of spin – clockwise and anticlockwise - that provides the different positive and negative aspects of a function.  For example ‘happiness’ and ‘sadness’ [a function of emotion].  Thus if the spin was negative and increased, the experiencer would go from sadness through extreme sadness to misery to abject despair [and presumably on to chronic depression].  Too much negative spin [and this sounds like a joke, but it isn’t meant to be]. 

Note that the spin quantum number may well be related to intensity of function, although this is speculation on my part.

In the diagram, if we were to separate out the atoms in the lattice we would end up with 2As, 1B, 3Cs, 1D and 1E, because mathematically this is the formula to 'make' an aggregate which we shall call F [say].  Whilst the bonds are formed, however, all the atoms give out the message that they are an aggregate F and their functions only reflect this state.  Thus in some senses for every unique aggregate, the signature is that set of functions which are active.  An aggregate is defined by its qualities/attributes/properties.  And each unique aggregate has a unique signature - set of properties. 

 

Atoms and Aggregates broadcast their properties on a continual basis as messages around the net, so with the right instrument - capable of picking up every single message, we would know the functions of every aggregate. 

But an instrument, even one of the Raman spectrometers mentioned above,  is an aggregate like anything else and will be limited in what it can pick up, not every message will be processed.  There may be messages coming from the ice for example that describe the property 'cold/freezing', but to get this message the instrument has to be able to accept it and understand it. 

Thus there are many aggregates - like us -  that are unable to process the message because the functions whose purpose is to process the message have a spin rate of zero – they are inactive.

Thus we cannot ‘see’ gases, they are invisible to us, the function that we have that might give us the ability to ‘see’ a gas has a spin rate of zero.  But certain sorts of ice [an aggregate] transmit the message that they are ‘blue’ and also ‘green’ [depending on the crystal they have formed] and we are able to ‘see’ green and blue as colours, because the functions for recognition of colours are active [spin rate non zero], so we can see green and blue ice.

A crystal of a specific type is ‘programmed’ to respond to the message from a source of light, for example the sun, which is constantly broadcasting the message ‘light’ [of all types].  Light is a quality - an attribute.  We have become confused by talking about wavelengths, when what we mean is actually a message over which superimposed are any number of qualities of 'light'.

The crystal receives the message ‘light’ which is then used to itself send out a set of messages relating to colour or temperature.  Raman’s effect is a spectrum of colours because each type of crystal has a unique set of functions ‘turned on’ – operational – that are its signature or fingerprint.

For those used to computers, the universe is analogously ‘programmed’ like an enormous message oriented middleware system, with messages flying about in all directions being processed by the collections of functions  ‘owned’ by an aggregate/atom.  The functions can respond to messages of various types and may also broadcast their properties and states.

Symbolic Sun = Creator
Recitation of the Gayatri mantra is preceded by oṃ (ॐ) and the formula bhūr bhuvaḥ svaḥ (भूर् भुवः स्वः), known as the mahāvyāhṛti ("great (mystical) utterance").

Life

 

Chandrasekhara Venkata Raman was born at Tiruchirappalli in Southern India on November 7th, 1888. He came from a Brahmin family, and although his father had become an agnostic as a student, his mother and all his relations had not.  His mother in particular was still a very devout Hindu.  His grandfather arranged for a paal-kaavadi ceremony at the Swamimalai temple prior to the upanayanam and at the upanayanam Raman was initiated into the sacred words of the gayatri mantra by his grandfather, his older brother and interestingly his father.

Throughout his life, Raman made no open displays of his beliefs, but there were a few tell tale signs that he was a Brahmin at heart.  He sported the tuft of hair – the few strands of uncut hair usually tied into a topknot that was seldom seen because he always wore a turban.  And he wore a sacred thread or poonal.  He remained vegetarian and he said his parisehanam at every meal taken at home.  The parisehanam is a short ritual where one pours water on the palm of one’s right hand, sprinkles a few drops around the leaf or plate on which the food is served and drinks what remains, intoning prescribed words of prayer.  This said, Raman was uninterested in the dogmas of religion.

There is another rather fascinating facet of Chandrasekhara Venkata’s beliefs, his father became very interested in theosophy in his later days, possibly through his neighbours Babu Govind Das and and Babu Bhagvan Das [the philosopher].  His father spent many hours discussing theosophy – which in India was essentially a set of spiritual beliefs based on mystical systems.  Govind Das and Bhagvan Das were at Venkata’s side several years later when he received news of his father’s death and their presence was ‘comforting at that difficult time’.

 

Venkata’s father was a lecturer in mathematics and physics so that from the first he was immersed in an academic atmosphere. After Raman's father became a lecturer in Mrs. A.V. Narasimha Rao College, Visakhapatnam (then Vishakapatnam) in the Indian state of Andhra Pradesh, the young Venkata Raman studied at St. Aloysius Anglo-Indian High School in Visakhapatnam. St. Aloysius was established in the year 1847 by the missionaries of St.Francis De Sales from France. It was thus a catholic school.  And it had such a reputation that “parents took great pains every day to drop their children from places far off”.   There is great value in comparing belief systems.

Raman passed his matriculation examination at the age of 11 and he passed his F.A. examination with a scholarship at the age of 13.  He entered Presidency College, Madras, in 1902, and in 1904 passed his B.A. examination, winning the first place and the gold medal in physics; in 1907 he gained his M.A. degree, obtaining the highest distinctions.

He was married on 6 May 1907 to Lokasundari Ammal (1892–1980). They had two sons, Chandrasekhar and radio-astronomer Radhakrishnan. 

Death

 

Professor Raman was active as the director of the Raman Research Institute in Bangalore, Karnataka until his death in Bangalore.  At the end of October 1970, he collapsed in his laboratory from a heart attack. After a few days in hospital he asked to be moved to the gardens of his Institute so that he could die there surrounded by his followers.  Professor Raman died early in the morning of 21 November 1970, aged 82.

Professor Raman, though brought up in both Hindu and Catholic traditions rarely talked about religion.  Nor did he openly practise it, but T S Satyan, the photographer who established a long term rapport with Raman, when relating the events of Raman’s 60^th birthday, described how the ayush homam prayers for a long life were performed  at Raman’s home Panchavati on the initiative of his wife and how ‘The whole house filled with smoke emanating from the sacred fire, and seemed to respond to the melodious chant of Vedic hymns’.

And he did make a number of rather telling comments. 

Atman is Brahman.

References

C.V. Raman: A Biography  -  Uma Parameswaran