| dc.description.abstract |
<p>Nanometer-scale metallic structures have been widely and intensively studied over
the last decade because of their remarkable plasmonic properties that can enhance
local electromagnetic (EM) fields. However, most plasmonic applications are restricted
to the visible and near infrared photon energies due to the limitations of the surface
plasmon resonance energies of the most commonly used plasmonic metals: Au and Ag.
Plasmonic applications in ultraviolet (UV) are of great interest because Raman scattering
sections are larger and do not overlap fluorescence spectra. UV plasmonics also benefit
from high spatial resolution and low penetration depth. However, an appropriate UV
plasmonic material must be identified.</p><p>We proposed and demonstrated that gallium
is a highly-promising and compelling material for UV nanoplasmonics through synthesis
of size-controlled nanoparticle arrays, EM modeling of local field enhancement, ellipsometric
and spatial characterization of the arrays, and analytical measurement of UV- enhanced
Raman and fluorescence spectra. Self-assembled arrays of hemispherical gallium nanoparticles
deposited by molecular beam epitaxy on a sapphire support are characterized with spatial
and ellipsometric measurements. Spin-casting a thin film of crystal violet upon these
nanoparticles permitted the demonstration of surface-enhanced Raman spectra, fluorescence,
and molecular photodegradation following excitation by a HeCd laser operating at 325
nm (UV). Measured local Raman enhancement factors exceeding 10<super>7</super> demonstrated
the potential of gallium nanoparticle arrays for plasmonically-enhanced ultraviolet
detection and remediation.</p>
|
|
