20 research outputs found
Optomechanics of Single Aluminum Nanodisks
Aluminum nanostructures
support tunable surface plasmon resonances and have become an alternative
to gold nanoparticles. Whereas gold is the most-studied plasmonic
material, aluminum has the advantage of high earth abundance and hence
low cost. In addition to understanding the size and shape tunability
of the plasmon resonance, the fundamental relaxation processes in
aluminum nanostructures after photoexcitation must be understood to
take full advantage of applications such as photocatalysis and photodetection.
In this work, we investigate the relaxation following ultrafast pulsed
excitation and the launching of acoustic vibrations in individual
aluminum nanodisks, using single-particle transient extinction spectroscopy.
We find that the transient extinction signal can be assigned to a
thermal relaxation of the photoexcited electrons and phonons. The
ultrafast heating-induced launching of in-plane acoustic vibrations
reveals moderate binding to the glass substrate and is affected by
the native aluminum oxide layer. Finally, we compare the behavior
of aluminum nanodisks to that of similarly prepared and sized gold
nanodisks
Spalling behaviors of Pb induced by ramp-wave-loading: Effects of the loading rise time studied by molecular dynamics simulations
Effects of dispersed copper nanoparticles on Ni-ceria based dry methanol fuelled low temperature solid oxide fuel cells
Polycrystallinity of Lithographically Fabricated Plasmonic Nanostructures Dominates Their Acoustic Vibrational Damping
The
study of acoustic vibrations in nanoparticles provides unique
and unparalleled insight into their mechanical properties. Electron-beam
lithography of nanostructures allows precise manipulation of their
acoustic vibration frequencies through control of nanoscale morphology.
However, the dissipation of acoustic vibrations in this important
class of nanostructures has not yet been examined. Here we report,
using single-particle ultrafast transient extinction spectroscopy,
the intrinsic damping dynamics in lithographically fabricated plasmonic
nanostructures. We find that in stark contrast to chemically synthesized,
monocrystalline nanoparticles, acoustic energy dissipation in lithographically
fabricated nanostructures is solely dominated by intrinsic damping.
A quality factor of <i>Q</i> = 11.3 ± 2.5 is observed
for all 147 nanostructures, regardless of size, geometry, frequency,
surface adhesion, and mode. This result indicates that the complex
Young’s modulus of this material is independent of frequency
with its imaginary component being approximately 11 times smaller
than its real part. Substrate-mediated acoustic vibration damping
is strongly suppressed, despite strong binding between the glass substrate
and Au nanostructures. We anticipate that these results, characterizing
the optomechanical properties of lithographically fabricated metal
nanostructures, will help inform their design for applications such
as photoacoustic imaging agents, high-frequency resonators, and ultrafast
optical switches