Raman Spectroscopy has been playing a central role in our understanding of different systems at molecular levels since its discovery. We have fabricated two custom built micro-Raman setup in our lab. One of them has a laser excitation of 532nm (green) to probe interactions in inorganic compounds and crystalline like structures. Other setup uses red laser to study specifically bio-molecular interactions. Recently we have been working for setting up polarization based Raman spectrometer for detection of Raman Optical Activity in biomolecules specially proteins.
Surface Enhanced Raman Spectroscopy:
SERS of Biomolecules:
There is a large interest in knowing the changes in biomolecules in their natural environment, such as, within a cell. Recent advancements have shown that gold and silver nanoparticles can be introduced into the cell without damaging and these attach to various parts of the cell. This enables us to look at the activities of these due to the enhancement in their Raman signals. The group is using SERS for two aspects
1) for diagnostics and
2) for interactions and structural information. We have been looking at protein and small molecular interactions using SERS in collaboration with Prof. Tapas K. Kundu in the field of Cancer Research. In this process we have been interested in producing different nano-structures of gold and silver in pure and core-shell architecture. We have been also interested in studying poly-peptides, nucleotides along with proteins. The group is also working in collaboration Prof. V. Nagaraja (IISc) to study the effect of metal ions on Restriction Enzyme KPN1. Surface Enhanced Raman Spectroscopy is also being used to study effect of small molecules binding in proteins. New nano structures are also being synthesized and characterized for studying the mechanism of SERS. Our group is also interested in theoretical simulations like FDTD (Finite Difference Time Domain), Molecular Dynamics, Gaussian etc. for better understanding SERS.
Single Molecule Detection: Using AFM tips we can localize the enhancement of raman signal and this in turn can be used to detect single molecule. This well known technique is known as Tip Enhanced Raman Spectroscopy. We are developing a customized TERS setup in our lab using Nanonics imaging setup along with our custom built Raman setup.
Brillouin spectroscopy is a non contact method to probe the elastic properties of materials. We have developed micro Brillouin setup in our lab which enables us to perform Brillouin investigations on micron sized samples as well. We have been looking at the elastic properties of various materials like metal organic frameworks, ionic liquids, pyrochlores, nanotubes etc. We have successfully developed high pressure Brillouin setup which is the first of its kind in India.
High pressure Raman spectroscopy
In- situ Raman spectroscopy is a widely used characterization technique for investigating the structural, vibrational and electronic properties of materials under high pressure. Using this technique, interesting phenomenon such as insulator metal transitions, lattice dynamics, amorphization, isostructural transitions, structural phase transitions, topological quantum phase transitions etc of materials can be investigated under extreme high pressure conditions.
Our present projects involves Topological insulators, High pressure structural transition, Insulator metal transitions and isostructural transitions studies.