Raman Spectroscopy, Surface-Enhanced Raman Spectroscopy, Fluorescence Spectroscopy, Surface-Enhanced Fluorescence Spectroscopy, Z-Scan Technique

The current research activities of my group in the domain of nanophotonics are evolving with Raman Spectroscopy, surface-enhanced Raman spectroscopy (SERS), fluorescence spectroscopy, surface-enhanced fluorescence spectroscopy (SEFS), and the Z-scan technique. The key focus of our research is to tune and maneuver the interaction of light with nanometer-scale objects (be they purely metallic, solely semiconducting, or metallic-semiconducting hybrids) and observe the concomitant effects through the aforementioned experimental techniques. To arrange the appropriate ingredients, we are preparing (mono)metallic nanoparticles of varying sizes, shapes, and morphology by both bottom-up (chemical, sonochemical, hydrothermal, and green syntheses) and top-down (laser ablation and sonochemical synthesis) techniques. By employing identical preparation routes and protocols, we are also fabricating bimetallic core-shell nanostructures with varying shapes, core sizes, shell thicknesses, and different types of highly fluorescent carbon nanodots. The prepared (monometallic and bimetallic) nanostructures and fluorescent nanodots are used to decorate the elongated surfaces of 2D semiconducting nanoflakes (2D ZnO and 2D MoS2) to produce various metallic-semiconducting heterostructure nanocomposites. Such heterostructure nanocomposites are found to serve as highly efficient SERS, SEFS and Z-Scan platforms, presumably due to an intense collection of super-active hotspots (of nanoparticles and nanodots) within the dielectric landscape of 2D semiconducting nanoflakes.

Stark Spectroscopy and Advanced Laser Spectroscopy (Single Molecule Spectroscopy and Transient Absorption Spectroscopy and Time-Resolved Fluorescence Spectroscopy) on natural, engineered photosynthetic pigment-protein complexes and their artificial analogs for precisely uncovering their biophysical molecular mechanisms and electronic structures associated with their Light-Harvesting and Regulative Energy Dissipation functions.

Natural photosynthesis has been a huge source of inspiration over the years for designing bio-inspired artificial devices for solar energy conversion and storage. To this end, achieving precise control on pigment organization and pigment-pigment/pigment-protein interactions is of the primary challenge in the design of artificial analogs of light-harvesting pigment-protein complexes. In such contex, precise mapping of the electronic structures and understanding of the strength and nature of Charge Transfer (CT) states of the mentioned natural, engineered photosynthetic antennas and their artificial analogs may be a good source of inspiration for designing and developing more versatile and efficient next generation natural /artificial solar energy conversion systems. Creation of artificial photosynthetic systems could meet the ever-increasing demand for cheap, environmentally clean energy for the generation to come.

The mentioned research are being performed in collaboration with different renowned and leading research groups around the globe (the Netherlands, Germany, England, Czech Republic, USA, Israel and Japan).

Stark Spectroscopy and other spectroscopic techniques to investigate the properties of some Organic Conjugated Polymers important for making light emitting diodes.

Collaborator: Dr. Linda A Peteanu, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA.

Stark Spectroscopy and other spectroscopic techniques to investigate the electronic structures and excite stated dynamics of a variety of Natural Carotenoids and their different Isomers to be used in Engineered and Artificial Photosynthetic pigment-protein analogs for harnessing better conversion efficiency.

Collaborator: Dr. Hideki Hashimoto, Kwansei Gakuin University, Sanda, Kobe, Japan.