What do We do?

Light is a tool to dwell into very small space and is the shortest scale in our reach to measure fastest events. Spectroscopic techniques have come a long way to unravel the mysteries of happening at molecular level.  We use these novel spectroscopic techniques for a better understanding of processes taking place in nature. You can read about basics on our resources page 

Any experiment in the laboratory begins with measuring steady state absorption and fluorescence spectra of the sample. We have JASCO V 770 UV-Vis-NIR (180nm to 3200 nmm) absorption spectrophotometer to measure absorption spectrum.  The absorption spectrum can recorded from 4 to 90 degree Celcius. We can also record absorbance and reflectance for solid samples using an integrating sphere.   

The sample is then taken to Cary Eclipse Spectrofluorimeter where the samples are checked for steady state lumeniscent properties. The wavelength range for its detection is 190 to 800 nm. We can carry out polarisation dependent measurements as well. Just like absorbance, here also we can do temperature dependent measurements between 4 and 90 degree centrigrade and can measure fluorescence from solid surfaces. 

We then proceed for doing Time resolved measurements. At IIT Goa, we are setting up femtosecond transient absorption spectroscopy setup. We have a Coherent Asterlla femtosecond ampliefied laser which produces ~35 fs pulses of energy ~5 mJ/pulse centred at 800 nm and operates at  1 kHz.  The output of the amplifier is directed to an OPA from ultrafast systems which can generate femtosecond pulses between 280 and 2200 nm. These are used as pump pulses for a pump-probe spectroscopic measurements. The probe pulse is a white light. The transient abosrption measurements are done on Helios Transient absorption spectrometer from ultrafast systems. The detection is done on a CCD spectrograph (320 nm-850 nm) and semiconductor spectrograph (850nm-1600 nm). 

Current projects going on in lab

Ultrafast Transient Spectro-Electrochemistry of Redox-Active Organic Molecules and their Radical Ions 

Spectro-electrochemistry, when combined with ultrafast spectroscopic techniques, help in understanding the charge transfer and recombination processes across various molecular systems.  The knowledge gained through these experiments will assist in designing novel systems to improve the performance of organic electronic devices and other light-harvesting entities. Several Organic molecules and their radicals demonstrate remarkable two-photon absorption (2PA), high photostability, and efficient intramolecular charge transfer (ICT) dynamics, supporting their role in nonlinear optical (NLO) applications. fs-TA-SEC can provide unique insights about electron transfer mechanisms, reak time monitoring excited state dynamics of electrochemical states.

Linear and Non-Linear Optical properties of Small organic molecules

Our lab investigates organic molecules using both linear and nonlinear spectroscopic techniques. These studies focus on probing their electronic transitions, vibrational dynamics, and excited-state behavior to unravel fundamental photophysical processes. Ultrafast spectroscopy provides insights into charge transfer and relaxation pathways, while nonlinear methods such as two-photon absorption and harmonic generation reveal hidden structural and electronic features. Together, these approaches help establish correlations between molecular architecture and optical response, advancing applications in sensing, photonics, and bioactive materials.

Spectroscopic investigation of marine molecules 

Visual pigments serve roles beyond vision, including energy harvesting. Biochemical and genetic studies reveal sequence similarities across species, though receptor structures remain unclear. Photoinitiation is ultrafast, with isomerization occurring in femtoseconds in higher organisms but slower in microbes. We propose to study pigments and metabolites from Indian seawaters and probing their photophysics via femtosecond absorption spectroscopy. This work will address unresolved questions on pigment function and evolution, potentially uncovering novel molecules with applications in biotechnology and cosmetics. It will be the first ultrafast spectroscopic study of microbial pigments from Indian waters.

Spectroscopic investigation of novel organometallic compounds

Development of renewable energy technologies as alternatives to fossil fuels is a crucial research area for a sustainable future, in order to meet ever growing global energy demands. In this regard metalloporphryins and transitional metal organometallic compounds have emerged as good candidates. However, the need of the hour is to prepare novel molecules with low bandgaps and easily tunable redox potentials, to improve the electron transfer rates and conductivity. Time resolved spectroscopy  will help to confirm the molecular structures and also unearth the energies of the frontier molecular orbitals and efficiencies of various electron transfer processes they can undergo. 

Excited state dynamics in nanomaterials

Research in our lab explores diverse nanomaterials such as perovskites, sulfur quantum dots, CdS nanorods, CdS–MOF hybrids, and BiVO₄–TiO₂ composites, with a focus on their optoelectronic and photocatalytic properties. These systems are engineered to enhance light absorption, charge separation, and stability, enabling applications in solar energy conversion, photocatalysis, and sensing. Ultrafast spectroscopy and advanced characterization techniques are employed to probe their interfacial dynamics and photophysics, while structural modifications at the nanoscale are designed to optimize performance. By integrating synthesis, spectroscopy, and modeling, the work aims to uncover fundamental mechanisms and develop functional nanomaterials for sustainable energy and environmental technologies.

Understanding ultrafast dynamics in the water-water interface 

Interfaces are central to physics, chemistry, and biology, shaping diverse applications since the earliest use of soap millennia ago. Emulsions, once thought limited to immiscible liquids like oil and water, rely on amphiphilic molecules that self-assemble or solvate hydrophobic compounds. Microemulsions mimic cellular hydrophobic environments, aiding studies of protein–drug interactions. While oil–water systems present stark contrasts, natural cells rarely show such extremes. Instead, water itself creates contrasting environments as bulk and interfacial phases. How molecular dynamics unfold at this water–water interface remains an intriguing question.

Research collaborators

Funding Agencies