Abstract :

I shall present the photoexcited hot carrier dynamics of low (1D and 2D) dimensional nanomaterials using time-resolved terahertz spectroscopy. Time-resolved terahertz (THz) spectroscopy offers non-contact measurement of conductivity in unexcited and photoexcited states of materials along with the carrier relaxation dynamics. I shall discuss the unique negative and positive photoconductivity responses of single-layer graphene (SLG), and bilayer gr aphene (BLG) in the 0.5-2.5 THz after photo excitation with 800 nm 50 fs optical pump pulse. These dynamical responses were understood by applying semi-classical Boltzmann transport theory for the hot carriers. Next, I shall briefly present the studies on photoexcited semiconducting nanowires showing plasmonic responses in the terahertz range. The detailed investigations of the plasmon dynamics provide non-contact measurement of intrinsic mobilities and surface recombination rates of these nanowires, which are essential for any optoelectronic device applications. Finally, I shall briefly present how the ultrafast hot carrier dynamics of nanostructures and nanomaterials can be extensively applied for intracellular research in the field of biomedical research.

Biography of the Speaker :
Dr. Srabani Kar did her Ph.D. in Physics from the Indian Institute of Science Bangalore on Time-resolved terahertz (THz) spectroscopy of low-dimensional materials in 2018. She then spent three years as a postdoctoral researcher at the University of Cambridge, UK, and one year at the Indian Institute of Technology Madras, India. She has been selected for 5-year Inspire Faculty Fellowship. Her research interests include ultrafast carrier dynamics, time-resolved terahe rtz spectroscopy, transient absorption spectroscopy, ultrafast light-matter interactions, and their applications in intracellular drug delivery. She aims to establish a THz research lab in the future to study fundamental physics, THz optoelectronic devices, and THz biomedical research.