Ultrafast lasers offer unique possibilities to control and probe transient processes in nanosystems. Following photoexcitation by a femtosecond laser pulse, the carrier dynamics includes many important issues like thermalization, energy relaxation, formation of excitons and spin dynamics which are impacted by dimensionality. Their understanding is crucial not only for many applications of nanomaterials such as fast modulators, photodetectors and solar cells, but also in designing new heterostructures and nano-hybrids. My talk will discuss some of our recent work on the dynamics of optical pump induced photocarriers in single and bilayer graphene, graphane, carbon nanotubes and transition metal dichalcogenides (TMD) as probed by time-resolved terahertz spectroscopy.<br/> <br/>A quantitative understanding of dynamic conductivity based on generalized Boltzmann transport model gives us insights into various relaxation mechanisms. The cooling of carriers in TMD is dominated by defect-assisted Auger scattering of photoexcited electrons, holes and excitons, primarily due to unscreened Coulomb interaction in 2D systems. Our recent work on Plasmon-assisted generation of hot carriers in graphene on an ultrathin gold film with periodic array of holes (showing anomalous transmission) as probed by transient absorption will also be mentioned.

Ultrafast photoresponse of 2D materials

256th National Meeting (2018)

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