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Nanoparticle-Enhanced Plasma Discharge Using Nanosecond High-Voltage Pulses
journal contribution
posted on 2020-03-23, 13:37 authored by Bofan Zhao, Indu Aravind, Sisi Yang, Zhi Cai, Yu Wang, Ruoxi Li, Sriram Subramanian, Patrick Ford, Daniel R. Singleton, Martin A. Gundersen, Stephen B. CroninBy
discharging nanosecond high-voltage (5 kV) pulses across an
insulating substrate containing Au, Pt, or Cu nanoparticles, a 3 order
of magnitude (1000×) enhancement in the generation of plasma
can be achieved through local field enhancement on the surface of
the nanoparticles. The low-temperature nature of this transient plasma
is crucial to maintaining the structural integrity of these delicate
nanoparticles. These nanoparticles provide up to a 1000-fold enhancement
in the generation of the plasma, which is localized to the surface
of the nanoparticles where it is potentially useful (e.g., for catalysis).
We performed both time-domain and frequency-domain calculations of
the electromagnetic response of the nanoparticles based on high-resolution
transmission electron microscope (HRTEM) images, which show local
field enhancement of the nanosecond high-voltage pulse on the order
of 3×. Since the plasma initiation depends exponentially on the
peak electric field strength, this 3-fold increase in the local electric
field can result in a several orders of magnitude increases in the
generation of plasma at a given applied external field strength. In
order to rule out plasmon-resonance enhancement, which is often associated
with small metal nanoparticles, we performed finite difference time
domain (FDTD) simulations in the optical frequency domain, which show
that the effect of plasmon resonance is negligible for Pt nanoparticles.
We therefore attribute the nanoparticle-based enhancement to the generation
of plasma (an electrostatic effect) rather than enhanced coupling
of light from the near field to the far field via the plasmon resonance
phenomenon (an optical effect).