My 60 Year Journey with the Raman Effect

Guest Contributor - Raman Kolluri

On December 9th 2025 I read an article that the Raman Effect is now being used to detect blood glucose levels without finger pricks. This news brought back memories of my own work in Raman Spectroscopy nearly sixty years ago. It is extraordinary that a discovery made almost one hundred years ago is still finding new and meaningful applications. The Raman Effect was discovered and published by C V Raman on February 16th 1928. He received the Nobel Prize in Physics for it in 1930.

My research journey began in 1960 and lasted for ten years. I started with basic equipment like mercury arc lamps and photographic plates in India, which led to my PhD in 1965. Later I continued my research using advanced equipment as a Postdoctoral Fellow at Johns Hopkins University in the United States. This write-up gives a simple overview of the Raman Effect and how I used it to study hydrogen bonding in liquids.

Understanding the Raman Effect

Raman Effect occurs when light interacts with molecules in a substance. Most light scatters without change but a small part scatters with a change in frequency. This happens because the light either gains or loses energy from the molecule's vibrations or rotations. This change in energy is called the Raman shift. It provides a kind of chemical fingerprint of the molecule.

Raman spectroscopy is very useful for identifying materials. The technique became much more powerful with the invention of the laser. Before lasers scientists did not have a good source of monochromatic light. Also the Raman signal is very weak and hard to detect without strong light sources.

Early Research in India

Before India gained independence scientific research there was not well supported. Even in 1960 most scientific equipment had to be imported. When I started my research in Raman spectroscopy the setup I used was similar to what C V Raman had used decades earlier.

My equipment included a mercury arc lamp for light, filters, a sample cell with liquid, a spectrograph, and photographic plates. It took three days and nights to capture a single spectrum. I recorded more than three hundred spectra during my research.

Discovering Hydrogen Bond Behavior

My work focused on hydrogen-bonded liquids such as water and nitric acid. In a water molecule there are two types of bonds between hydrogen and oxygen. One is a strong covalent bond and the other is a weaker hydrogen bond.

These two bonds exchange their roles at a specific frequency. This is known as the flicker cluster frequency, a theory proposed by Professor H D Long. My goal was to prove this experimentally using Raman spectroscopy. After five years of hard work I succeeded and received my PhD in 1965.

Work at Johns Hopkins University

In 1966 I joined Professor Cummins as a Postdoctoral Fellow at Johns Hopkins University. There we studied a crystal called strontium titanate. The goal was to find out if it had a ferroelectric state at low temperature.

The lab had advanced tools. We used a stainless steel cryostat cooled with liquid nitrogen and helium. We also used one of the first argon ion lasers. The spectra appeared directly on a recorder. Compared to my setup in India this was a huge improvement. We successfully found the ferroelectric state and published our results.

Later Years and Continued Encounters

After 1970 I moved into laser technology and materials science. When I returned to the United States in 1985 I trained laser technicians. In 2002 at a laser conference in Copenhagen I heard a paper suggesting that a Raman signal could be used as a carrier in optical fibers.

They explained that Raman lines are very pure with no side frequencies. Using Raman lines could reduce losses in fiber optics. Another idea they proposed was to use vacuum instead of glass to prevent light absorption. This was another sign that the Raman Effect was continuing to evolve and inspire new solutions.

Modern Applications and Reflection

In 2025 the latest news is that Raman spectroscopy is being used to measure blood glucose. Glucose molecules have a specific Raman shift at 1125. This can be compared to the hemoglobin signal at 1549. Using lasers in the near-infrared range and data filtering techniques scientists can now separate the glucose signal from other tissue signals.

This makes it possible to check blood sugar without pricking the skin. As someone who worked with Raman spectroscopy from its early days I feel amazed and grateful that this discovery continues to help people.

Final Thoughts

I retired in 2010. But the journey I began in the 1960s still lives on. A single scientific discovery can have a long and powerful impact. I feel blessed to have contributed in a small way to a field that continues to bring new hope and applications to the world.