4 research outputs found
Photoluminescence of Gold Nanorods: Purcell Effect Enhanced Emission from Hot Carriers
We demonstrate, experimentally and
theoretically, that the photon
emission from gold nanorods can be viewed as a Purcell effect enhanced
radiative recombination of hot carriers. By correlating the single-particle
photoluminescence spectra and quantum yields of gold nanorods measured
for five different excitation wavelengths and varied excitation powers,
we illustrate the effects of hot carrier distributions evolving through
interband and intraband transitions and the photonic density of states
on the nanorod photoluminescence. Our model, using only one fixed
input parameter, describes quantitatively both emission from interband
recombination and the main photoluminescence peak coinciding with
the longitudinal surface plasmon resonance
Multifunctional Au–Co@CN Nanocatalyst for Highly Efficient Hydrolysis of Ammonia Borane
A magnetically
recyclable carbon nitride supported Au–Co
nanoparticles (Au–Co@CN) displayed exceedingly high photocatalytic
activity for hydrolysis of aqueous ammonia borane (NH<sub>3</sub>BH<sub>3</sub>, AB) solution. Combined with a synergetic effect between
Au and Co nanoparticles, the Motty–Schottky effect at the metal–semiconductor
interface remarkably facilitated the catalytic performance of the
Au–Co@CN catalyst on the hydrolysis of AB. The TOF value of
Au–Co@CN catalyst is 2897 mol H<sub>2</sub> mol<sup>–1</sup> metal h<sup>–1</sup> at 298 K under visible light irradiation,
which is more than 3 times higher than that of the benchmarked catalyst,
PVP-stabilized Au@Co nanoparticles
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
Optimization of Spectral and Spatial Conditions to Improve Super-Resolution Imaging of Plasmonic Nanoparticles
Interactions
between fluorophores and plasmonic nanoparticles modify
the fluorescence intensity, shape, and position of the observed emission
pattern, thus inhibiting efforts to optically super-resolve plasmonic
nanoparticles. Herein, we investigate the accuracy of localizing dye
fluorescence as a function of the spectral and spatial separations
between fluorophores (Alexa 647) and gold nanorods (NRs). The distance
at which Alexa 647 interacts with NRs is varied by layer-by-layer
polyelectrolyte deposition while the spectral separation is tuned
by using NRs with varying localized surface plasmon resonance (LSPR)
maxima. For resonantly coupled Alexa 647 and NRs, emission to the
far field through the NR plasmon is highly prominent, resulting in
underestimation of NR sizes. However, we demonstrate that it is possible
to improve the accuracy of the emission localization when both the
spectral and spatial separations between Alexa 647 and the LSPR are
optimized