Controlling and Understanding Atomic-Scale Dynamics within Plasmonic Nanogaps
type: CreativeWork
description: Plasmonic nanogaps, such as the ∼1 nm gaps between two gold surfaces in a nanoparticle-on-mirror (NPoM) structure, are able to confine light to nanoscale volumes and enhance optical fields by orders of magnitude. This enhancement allows a few hundred molecules placed in this gap, such as biphenyl-4-thiol, to be probed by techniques like surface-enhanced Raman spectroscopy (SERS). In addition, the enhanced fields induce a range of atomic-scale dynamics in the gap, resulting in blinking emission phenomena such as picocavities and plasmonic flares. Picocavities are fleeting narrow-band spectral lines attributed to transiently forming metallic adatoms that confine light to a <1 nm3 volume, inducing stronger SERS from a nearby single molecule. Flares are flashes of broadband emission explained by patches of the metal surface peeling off and enhancing metal emission. In this thesis, optical control over formation and stability of picocavity adatoms is first explored. Such control is achieved by pulses of visible light on an NPoM, where they rapidly write an adatom in the nanogap. The adatoms are shown to be storable in ambient conditions for up to a week in the dark and are read using low-intensity SERS. Writing at higher optical intensities stabilises the atomic protrusion through light-induced local restructuring. Fluctuations in the picocavity SERS spectra show that light also accelerates the energy landscape exploration by the adatom. Optical control over single metal atom dynamics opens promising avenues for next-generation microelectronics and catalysis. Next, the nanogap blinking is studied at 10 μs time resolution to expand the mechanistic understanding of the associated atomic-scale dynamics. To maximise the detection of these fast fluctuations, a custom avalanche photodiode (APD) device is built, capable of 10 μs resolution with negligible read noise contribution. Furthermore, superefficient plasmonic nanoarchitectures for Raman kinetics (SPARKs) are implemented…
abstract: Plasmonic nanogaps, such as the ∼1 nm gaps between two gold surfaces in a nanoparticle-on-mirror (NPoM) structure, are able to confine light to nanoscale volumes and enhance optical fields by orders of magnitude. This enhancement allows a few hundred molecules placed in this gap, such as biphenyl-4-thiol, to be probed by techniques like surface-enhanced Raman spectroscopy (SERS). In addition, the enhanced fields induce a range of atomic-scale dynamics in the gap, resulting in blinking emission phenomena such as picocavities and plasmonic flares. Picocavities are fleeting narrow-band spectral lines attributed to transiently forming metallic adatoms that confine light to a <1 nm3 volume, inducing stronger SERS from a nearby single molecule. Flares are flashes of broadband emission explained by patches of the metal surface peeling off and enhancing metal emission. In this thesis, optical control over formation and stability of picocavity adatoms is first explored. Such control is achieved by pulses of visible light on an NPoM, where they rapidly write an adatom in the nanogap. The adatoms are shown to be storable in ambient conditions for up to a week in the dark and are read using low-intensity SERS. Writing at higher optical intensities stabilises the atomic protrusion through light-induced local restructuring. Fluctuations in the picocavity SERS spectra show that light also accelerates the energy landscape exploration by the adatom. Optical control over single metal atom dynamics opens promising avenues for next-generation microelectronics and catalysis. Next, the nanogap blinking is studied at 10 μs time resolution to expand the mechanistic understanding of the associated atomic-scale dynamics. To maximise the detection of these fast fluctuations, a custom avalanche photodiode (APD) device is built, capable of 10 μs resolution with negligible read noise contribution. Furthermore, superefficient plasmonic nanoarchitectures for Raman kinetics (SPARKs) are implemented…
author: Kerner, Paul
language: eng
keywords: dynamics, picocavity, plasmonics, SERS
license: https://www.repository.cam.ac.uk/bitstreams/3f434cf7-6976-4685-aba1-2fb6e58d8942/download
license: https://creativecommons.org/licenses/by/4.0/
date published: 2025-09-30
date modified: 2026-07-22T22:24:04Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.127841