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.
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.