(CANCELED) Mahi R. Singh (The University of Western Ontario)

Date: Mon. September 12th, 2022, 12:45 pm-1:45 pm
Location: Rockefeller 221 (Foldy) & Zoom
Website: https://physics.uwo.ca/~msingh/home/index.html

CANCELED

 

Light-Matter Interaction in Graphene and Metallic Nanoparticles Nanohybrids  

Mahi R. Singh, 

Department of Physics and Astronomy,  Vanderbilt University, Nashville, USA 

Western University, Ontario, London, Canada N6A 3K7 

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Abstract.–There is considerable interest in light-matter interaction by combining plasmonic materials such as graphene and metallic nanoparticles with quantum dots. Graphene was invented theoretically by Wallace in 1947 [1] and he found that graphene is a gapless material. Later, Wallace and I found additional gapless materials, such as narrow-gap semiconductors which have direct band gaps [2]. Graphene-like gapless materials contain surface plasmons which interact with light and create new types of particles called surface plasmon polaritons (SPPs) and phonon plasmon polaritons (PPPs). The SPPs in graphene can be tunable via the electrostatic gating technique. Graphene has also emerged as a very promising candidate for terahertz to visible frequency applications since its plasmonic resonance frequency lies within this range [3]. The aim of this talk is to discuss the light-matter interaction between graphene and metallic nanoparticle nanohybrids. We discovered that when the exciton energy of the quantum dots is in resonance with the SPP and PPP energies the absorption, scattering cross-section, and photoluminescence in the quantum dots are enhanced in the terahertz range. The enhancement is due to the transfer of SPP and PPP energies from the plasmonic materials to the quantum dots. The energy transfer from the graphene to the quantum dots can be controlled by applying external pump lasers or stress and strain fields. This means that the energy transfer from the quantum dots to the graphene can be switched ON and OFF by external ultrafast lasers. These are interesting findings which can be used to fabricate new types of nanoswitches and nanosensors for applications in nanotechnology and nanomedicine. 

1. P. R. Wallace, Phys. Rev. 71, 622 (1947). 
2. M. Singh, P. R. Wallace, J. Phys. C 20, 2169 (1987); J. Phys. C 16, 3877 (1983). 
3.  J. Cox et al., Phys. Rev. B 86, 125452 (2012), M.. Singh et al., J. Appl. Phys. 120, 124308 (2016).

Host: Harsh Mathur