Chandrasekhara Venkata Raman, a renowned physicist from India, is celebrated for his groundbreaking contributions to the study of light scattering. Collaborating with his student K. S. Krishnan, Raman observed the phenomenon where light alters its wavelength and frequency upon passing through a transparent medium. This pivotal discovery, now known as the Raman Effect, earned him the Nobel Prize in Physics in 1930, making him the first Asian to achieve such an honor in the realm of science. Utilizing a quartz spectrograph, Raman meticulously determined the wavelengths of scattered light, revolutionizing our understanding of optical phenomena. In recognition of his exceptional achievements, the Government of India bestowed upon him the inaugural Bharat Ratna, the highest civilian award, in 1954.
About
Raman, born to Tamil Brahmin parents, finished high school at St Aloysius Anglo-Indian High School by 13. At 16, he excelled in physics at the University of Madras Presidency College. While still a grad student, he presented his initial research on light diffraction in 1906.
Inspiration hit him during his maiden European voyage when he questioned why the Mediterranean Sea appeared blue. This sparked his pioneering work on the Raman Effect, unveiled in 1922 and officially confirmed on February 28, 1928, with his invention, the spectrograph. His groundbreaking discovery earned him the Nobel Prize in Physics in 1930. Later, in 1933, he became the inaugural Indian director of the Indian Institute of Science in Bangalore, where he continued his scientific endeavors. He subsequently founded the Raman Research Institute in 1948, where he dedicated his efforts until his demise.
Raman Spectroscopy
Raman spectroscopy, a widely used method in chemistry, helps identify molecular vibrations, including low-frequency and spinning motion. It uses inelastic photon scattering called Raman scattering. Typically, a laser is used, spanning visible, near-ultraviolet, or near-infrared wavelengths, though X-rays can also work.
The challenge in Raman spectroscopy is distinguishing weak, inelastically scattered light from intense Rayleigh scattered laser light, known as “laser rejection.” Commonly used spectrographs often employ single-stage designs like axial transmissive or Czerny-Turner monochromators with CCD detectors. Alternatively, researchers use Fourier transform spectrometers, especially with near-infrared lasers.
Raman Effect
When molecules deflect light, they change its wavelength and frequency. In a clear chemical sample, some light deviates from the incident beam, known as the Raman effect, discovered by Sir Chandrasekhara Venkata Raman in 1928. This effect produces light with different wavelengths alongside the original. It’s typically faint, with intensity as low as 1/100,000 of the incident beam’s power in liquid compounds. The pattern of Raman lines is unique to each molecule, with line strength proportional to the number of scattering molecules.
Conclusion
In 1928, Sir Chandrasekhara Venkata Raman found that certain types of light cause transparent materials to emit light at different frequencies. This phenomenon, known as Raman frequencies, occurs when light interacts with the rotational and vibrational states of molecules. Raman also investigated how ultrasonic and hypersonic waves diffract light, and the effects of X-rays on infrared vibrations in crystals.
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