National Science Day is celebrated in India on February 28th each year to commemorate the discovery of the Raman effect by Sir C.V. Raman. This day is dedicated to the field of science and aims to instill a scientific temper among the people and encourage scientific development in the country

THEME 2024 – “Indigenous Technologies for Viksit Bharat”

SIR CV RAMAN

• Sir Chandrasekhara Venkata Raman
• Indian physicist
• Born on November 7, 1888, in Tiruchirapalli, Madras Province, British India (now in Tamil Nadu, India)
• Obtained his Bachelor’s degree in Physics from Presidency College, Madras (now Chennai), and later pursued his Master’s degree from the University of Madras
• Started his career as an assistant accountant general in the Indian Finance Service but soon shifted his focus to research in physics. In 1917, he joined the University of Calcutta as a lecturer in the Department of Physics
• In 1928, while working at the Indian Association for the Cultivation of Science in Calcutta (now Kolkata), Raman made his groundbreaking discovery of the Raman effect
• C.V. Raman was awarded the Nobel Prize in Physics in 1930 for his work on the scattering of light and the discovery of the Raman effect. He became the first Asian and the first non-white person to receive a Nobel Prize in any branch of science
• In 1948, Raman established the Raman Research Institute in Bangalore (now Bengaluru), India. The institute became a hub for research in physics and allied sciences
• Apart from the Raman effect, C.V. Raman made notable contributions to various areas of physics, including acoustics and optics. He also conducted research on the physics of musical instruments
• In addition to the Nobel Prize, C.V. Raman received numerous honors and awards, both in India and internationally. He was knighted in 1929 but chose to use the honorific “Sir” only in the academic and scientific context
•  C.V. Raman continued his research and educational efforts throughout his life. He passed away on November 21, 1970. His legacy lives on through the Raman effect, which remains a fundamental technique in molecular spectroscopy. The Raman Research Institute in Bangalore continues to contribute to scientific research.
• C.V. Raman’s life and work have inspired generations of scientists in India and around the world. His dedication to scientific inquiry, coupled with his pioneering discoveries, has left an enduring impact on the field of physics

RAMAN EFFECT

At its core, the Raman effect elucidates the changes in the wavelength of scattered light when it interacts with matter. This phenomenon is particularly profound when considering the molecular vibrations and rotations within a material. To comprehend the Raman effect, one must delve into the fascinating interplay between incident light and the vibrational modes of molecules.

Understanding the Basics: Light Scattering and Frequency Shifts

When monochromatic light, characterized by a single color or frequency, impinges on a material, the majority of the scattered light retains the same frequency as the incident light. This phenomenon, known as Rayleigh scattering, dominates the scattering process. However, a fraction of the scattered light exhibits a different frequency, marking the essence of the Raman effect.

The frequency shift observed in the Raman effect is a consequence of the energy changes associated with the vibrational and rotational modes of the molecules within the material. This shift provides a unique fingerprint that allows scientists to unravel the molecular symphony concealed within substances.

The Two Faces of Raman Scattering: Rayleigh and Raman Components

Within the Raman effect, two types of scattering processes come to the fore: Rayleigh scattering and Raman scattering.

1. Rayleigh Scattering: This primary process constitutes the bulk of the scattering, with the scattered light maintaining the same frequency as the incident light. While crucial, Rayleigh scattering often overshadows the subtler Raman scattering.
2. Raman Scattering: This secondary process introduces a small fraction of scattered light with a different frequency. The frequency shift reflects the energy associated with the molecular vibrations, providing a spectral signature that enables scientists to discern the underlying molecular architecture.

C.V. Raman’s Pioneering Work: A Nobel Prize-worthy Discovery

C.V. Raman’s eureka moment occurred when he observed the Raman effect in 1928. The experimental setup involved directing sunlight through a liquid, with the scattered light passing through a spectrograph. Raman noticed distinct lines in the spectrum that did not align with the incident light, marking the birth of the Raman effect.

In recognition of his groundbreaking work, C.V. Raman was awarded the Nobel Prize in Physics in 1930. His discovery not only affirmed the dual nature of light but also opened a new avenue for studying molecular structures, laying the foundation for Raman spectroscopy.

Applications of Raman Spectroscopy: Peering into Molecular Worlds

Raman spectroscopy, the offspring of the Raman effect, has emerged as a versatile tool with far-reaching applications across scientific disciplines. The technique involves shining a monochromatic light on a sample and analyzing the scattered light to unveil the molecular composition and structure.

1. Chemistry: Raman spectroscopy serves as a potent analytical tool in chemistry, enabling researchers to identify and characterize molecules. It allows for the non-destructive analysis of chemical compounds, facilitating advancements in fields such as organic chemistry and chemical engineering.
2. Physics: The study of molecular vibrations and rotations through Raman spectroscopy has profound implications in the field of physics. It provides insights into the energy levels and quantum states of molecules, contributing to our understanding of fundamental physical principles.
3. Biology: In the realm of biology, Raman spectroscopy plays a crucial role in examining biological molecules. It aids in the identification of biomolecules, offering a non-invasive method for studying cells and tissues. This has implications for medical diagnostics and pharmaceutical research.
4. Materials Science: Raman spectroscopy is a cornerstone in materials science, providing a means to investigate the composition and structural properties of materials. From semiconductors to polymers, researchers leverage Raman spectroscopy to unravel the secrets held within diverse materials.
5. Environmental Science: Raman spectroscopy finds applications in environmental science, allowing for the analysis of pollutants, contaminants, and environmental samples. Its non-destructive nature and high specificity make it a valuable tool for environmental monitoring.

Challenges and Advancements: Pushing the Boundaries of Raman Spectroscopy

While Raman spectroscopy has proven to be a formidable analytical technique, it is not without its challenges. One primary limitation is the relatively weak intensity of Raman scattering, necessitating sensitive detection methods. Advances in technology, such as the development of high-sensitivity detectors and laser sources, have significantly enhanced the capabilities of Raman spectroscopy.

In recent years, innovations such as surface-enhanced Raman spectroscopy (SERS) and coherent anti-Stokes Raman spectroscopy (CARS) have further extended the reach of Raman techniques. SERS amplifies the Raman signal by utilizing nanostructured surfaces, while CARS provides enhanced sensitivity and faster data acquisition.