In this work, we proposed new shape nanoparticles in the name of supershape nanoparticles by manipulation in the morphology of a disk nanoparticle. The electric field distribution of supershape nanoparticles were investigated at resonance wavelength of particle plasmons. The effects of dispersed medium and different sensory materials on particle plasmons were reported. The obtained results showed that there exist the multiple plasmonics modes in supershape nanoparticles. We found that the high sensitivity factor is available in the supershape nanoparticles. This study can be a base for the characterization of multiple particle plasmons in plasmonic devices for sensing applications.
We report on the manipulation of magnetization by femtosecond laser pulses in a periodic array of cylindrical nickel nanoparticles. By performing experiments at different wavelength, we show that the excitation of collective surface plasmon resonances triggers demagnetization in zero field or magnetic switching in a small perpendicular field. Both magnetic effects are explained by plasmon-induced heating of the nickel nanoparticles to their Curie temperature. Model calculations confirm the strong correlation between the excitation of surface plasmon modes and laser-induced changes in magnetiza…
Understanding and controlling properties of plasmon-induced hot carriers is a key step towards next-generation photovoltaic and photocatalytic devices. Here, we uncover a route to engineering hot-carrier generation rates of silver nanoparticles by designed embedding in dielectric host materials. Extending our recently established quantum-mechanical approach to describe the decay of quantized plasmons into hot carriers we capture both external screening by the nanoparticle environment and internal screening by silver d-electrons through an effective electron-electron interaction. We find that h…
The optical and morphological properties of hollow gold nanoparticles (HGNPs) can be finely modified by employing Poly-L-Lysine hydrobromide (PLL), an homo poly aminoacid of the L-lysine, used as reducer and stabilizer. We investigate locally the plasmonic response of these nanostructures by electron energy loss spectroscopy (EELS). The plasmon excitations are interpreted by discrete dipolar approximation (DDA) simulations. We demonstrate that this controlled top-down morphological modification a fine tuning of the optical response is possible. Unlike the traditional lithographic techniques, t…
Harnessing hot electrons and holes resulting from the decay of localized surface plasmons in nanomaterials has recently led to new devices for photovoltaics, photocatalysis and optoelectronics. Properties of hot carriers are highly tunable and in this work we investigate their dependence on the material, size and environment of spherical metallic nanoparticles. In particular, we carry out theoretical calculations of hot carrier generation rates and energy distributions for six different plasmonic materials (Na, K, Al, Cu, Ag and Au). The plasmon decay into hot electron-hole pairs is described …
The present paper deals with the systematic growth of plasmonic gold nanoparticles (Au NPs) on molybdenum disulphide (MoS$_2$) nanosheets as well as the effect of Au NPs on the optical and magnetic properties. The crystalline nature of the nanocomposites is confirmed by X-ray diffraction and transmission electron microscopic techniques. The optical properties are characterized using absorption and Raman spectroscopic techniques. The electron paramagnetic resonance technique is used to study the magnetic response of the nanocomposites. The paper attempts to gain a fundamental understanding of t…
Gallium is a plasmonic material offering ultraviolet to near-infrared tunability, facile and scalable preparation, and good stability of nanoparticles. In our contribution, we experimentally demonstrate the link between the shape and size of individual gallium nanoparticles and their optical properties. To this end, we utilize scanning transmission electron microscopy combined with electron energy loss spectroscopy. Lens-shaped gallium nanoparticles with a diameter between 10 nm and 200 nm were grown directly on a silicon nitride membrane using an in-house developed effusion cell operated at u…
Optical properties of colloidal plasmonic titanium nitride nanoparticles are examined with an eye on their photothermal via transmission electron microscopy and optical transmittance measurements. Single crystal titanium nitride cubic nanoparticles with an average size of 50 nm exhibit plasmon resonance in the biological transparency window. With dimensions optimized for efficient cellular uptake, the nanoparticles demonstrate a high photothermal conversion efficiency. A self-passivating native oxide at the surface of the nanoparticles provides an additional degree of freedom for surface funct…
Flat TiO$_2$ layers are deposited by magnetron sputtering on Ti/Si wafers. The TiO$_2$ surfaces are then sputter-coated with thin Au films of a nominal thickness of 0.5-10 nm that are converted by solid-state dewetting into Au nanoparticles of tuneable size and spacing; the Au nanoparticle size can be tuned over a broad range, i.e. ca. 3-200 nm. The Au-decorated TiO$_2$ surfaces enable plasmonic photo-electrochemical water splitting under visible light illumination (450-750 nm). The water splitting performance reaches a maximum for TiO$_2$ layers decorated with ~ 30 nm-sized Au particles. As e…
We present an approach to master the well-known challenge of calculating the contribution of d-bands to plasmon-induced hot carrier rates in metallic nanoparticles. We generalise the widely used spherical well model for the nanoparticle wavefunctions to flat d-bands using the envelope function technique. Using Fermi's golden rule, we calculate the generation rates of hot carriers after the decay of the plasmon due to transitions from either a d-band state to an sp-band state or from an sp-band state to another sp-band state. We apply this formalism to spherical silver nanoparticles with radii …
Assemblies of closely separated gold nanoparticles exhibit a strong collective plasmonic response due to coupling of the plasmon modes of the individual nanostructures. In the context of self-assembly of nanoparticles, closed packed 2D clusters of spherical nanoparticles present an important composite system that promises numerous applications. The present study probes the collective plasmonic characteristics and resulting photothermal behavior of closed packed 2D Au nanoparticle clusters in order to delineate the effects of cluster size, inter-particle distance and particle size. Smaller nano…
Formation of surface plasmon modes in sodium nanoclusters containing 20-300 atoms was studied using the GW method. It is shown that in the small Na nanoparticles up to 2 nm in size, the loss function $Im[ε^{-1}]$ is dominated by a single peak corresponding to localized surface plasmon resonance (LSPR). For particles of 2 nm and more, a resonance corresponding to surface plasmon polariton (SPP) oscillations begins to form, as well as a resonance corresponding to volume plasmon (VP) excitations. Considering the above, the linear size of a particle in the range of 0.7-3.7 nm can be estimated as t…
Plasmonic nanoparticles from unconventional materials can improve or even bring some novel functionalities into the disciplines inherently related to plasmonics such as photochemistry or (spectro)electrochemistry. They can, for example, catalyze various chemical reactions or act as nanoelectrodes and optical transducers in various applications. Silver amalgam is the perfect example of such an unconventional plasmonic material, albeit it is well-known in the field of electrochemistry for its wide cathodic potential window and strong adsorption affinity of biomolecules to its surface. In this st…
We utilize experimental tools such as conductive atomic force microscopy and electrostatic force microscopy on photo-excited arrays of gold nanoparticles on indium tin oxide substrate. The nanoparticles are partially covered by a thin semiconductor polymer. The change in the current and potential profiles of the composite metal-semiconductor sample after excitation at plasmonic resonance frequency of metallic nanoparticles is analyzed.
The incorporation of noble metal nanoparticles, displaying localized surface plasmon resonance, in the active area of donor-acceptor bulk-heterojunction organic photovoltaic devices is an industrially compatible light trapping strategy, able to guarantee better absorption of the incident photons and give an efficiency improvement between 12% and 38%. In the present work, we investigate the effect of Au and Ag nanoparticles blended with P3HT: PCBM on the P3HT crystallization dynamics by synchrotron grazing incidence X-ray diffraction. We conclude that the presence of (1) 80nm Au, (2) mix of 5nm…
We report the investigation of the generation and detection of GHz coherent acoustic phonons in plasmonic gold nanoparticles superlattices (NPS). The experiments have been performed from an optical femtosecond pump-probe scheme across the optical plasmon resonance of the superlattice. Our experiments allow to estimate the collective elastic response (sound velocity) of the NPS as well as an estimate of the nano-contact elastic stiffness. It appears that the light-induced coherent acoustic phonon pulse has a typical in-depth spatial extension of about 45 nm which is roughly 4 times the optical …
We demonstrate scaffolding of plasmonic nanoparticles by topological defects induced by colloidal microspheres to match their surface boundary conditions with a uniform far-field alignment in a liquid crystal host. Displacing energetically costly liquid crystal regions of reduced order, anisotropic nanoparticles with concave or convex shapes not only stably localize in defects but also self-orient with respect to the microsphere surface. Using laser tweezers, we manipulate the ensuing nanoparticle-microsphere colloidal dimers, probing the strength of elastic binding and demonstrating self-asse…
Bimetallic plasmonic nanoparticles enable tuning of the optical response and chemical stability by variation of the composition. The present numerical simulation study compares Ag-Au alloy, Ag@Au core-shell, and Au@Ag core-shell bimetallic plasmonic nanoparticles of both spherical and anisotropic (nanotriangle and nanorods) shapes. By studying both spherical and anisotropic (with LSPR in the near-infrared region) shapes, cases with and without interband transitions of Au can be decoupled. Explicit comparisons are facilitated by numerical models supported by careful validation and examination o…
We theoretically investigate equilibrium behaviors and photothermal effects of a flexible plasmonic metamaterial composed of aramid nanofibers and gold nanoparticles. The fiber matrix is considered as an external field to reconfigure a nanoparticle assembly. We find that the heating process tunes particle-particle and fiber-particle interactions, which alter adsorption of nanoparticles on fiber surfaces or clustering in pore spaces. Thus, it is possible to control the nanoparticle self-assembly by laser illumination. Gold nanoparticles strongly absorb radiations and efficiently dissipate absor…
Metal nanoparticles are attractive for plasmon-enhanced generation of hot carriers, which may be harnessed in photochemical reactions. In this work, we analyze the coherent femtosecond dynamics of photon absorption, plasmon formation, and subsequent hot-carrier generation through plasmon dephasing using first-principles simulations. We predict the energetic and spatial hot-carrier distributions in small metal nanoparticles and show that the distribution of hot electrons is very sensitive to the local structure. Our results show that surface sites exhibit enhanced hot-electron generation in com…
Spatial confinement of matter in functional nanostructures has propelled these systems to the forefront of nanoscience, both as a playground for exotic physics and quantum phenomena and in multiple applications including plasmonics, optoelectronics, and sensing. In parallel, the emergence of monochromated electron energy loss spectroscopy (EELS) has enabled exploration of local nanoplasmonic functionalities within single nanoparticles and the collective response of nanoparticle assemblies, providing deep insight into the associated mechanisms. However, modern synthesis processes for plasmonic …
Design of nanoscale structures with desired nanophotonic properties are key tasks for nanooptics and nanophotonics. Here, the correlative relationship between local nanoparticle geometries and their plasmonic responses is established using encoder-decoder neural networks. In the im2spec network, the correlative relationship between local particle geometries and local spectra is established via encoding the observed geometries to a small number of latent variables and subsequently decoding into plasmonic spectra; in the spec2im network, the relationship is reversed. Surprisingly, these reduced …
We present a rigorous theoretical model for the optical interaction between a nitrogen-vacancy (NV) centre in diamond and a plasmonic metal nanoparticle (MNP), accompanied by a computationally efficient procedure to solve the evolution. The proposed model enables us to successfully explain existing optical emission measurements of NV centres both in the presence and absence of a metal nanoparticle. We show that the NV-plasmon interaction provides a versatile new avenue to enhance and control the optical emission of an NV centre. Changes to the MNP type and size, NV-MNP centre separation, subme…
Self-organized monocrystalline Au nanoparticles with potential applications in plasmonics are grown in a SrTiO$_3$ matrix by a novel two-step deposition process. The crystalline preferred orientation of these Au nanoparticles is investigated by synchrotron hard x-ray diffraction. Nanoparticles preferentially align with the (111) direction along the substrate normal (001), whereas two in-plane orientations are found with $[110]_{SrTiO_3} \: || \: [110]_{Au}$ and $[100]_{SrTiO_3} \: || \: [110]_{Au}$. Additionally, a smaller diffraction signal from nanoparticles with the (001) direction parallel…
The adsorption of hydrogen on Au nanoparticles (NPs) of size of the order of 10 nm has been investigated by use of localised surface plasmon resonances (LSPR) in the NPs. The samples, formed by Au NPs obtained by oblique angle deposition on glass substrates, display a strong optical dichroism due to two different plasmon resonances dependent on the polarisation of light. This ensured the use of Transmittance Anisotropy Spectroscopy, a sensitive derivative optical technique, which permitted one to measure shifts of the LSPR as small as 0.02 nm upon H adsorption, which is not accessible by conve…
It is a generally accepted idea that the particle size distribution strongly affects the optical spectra of colloidal plasmonic nanoparticles. It is often quoted as one of the main reasons while explaining the mismatch between the theoretical and experimental optical spectra of such nanoparticles. In this work, these aspects are critically analyzed by means of a bottom up statistical approach that considers variables such as mean, standard deviation and skewness of the nanoparticle size distribution independently from one another. By assuming normal and log-normal distributions of the particle…
