Surface Enhanced Raman Spectroscopy (SERS) is exploited here to investigate the interaction of isolated sp carbon chains (polyynes) in a methanol solution with silver nanoparticles. Hydrogen-terminated polyynes show a strong interaction with silver colloids used as the SERS active medium revealing a chemical SERS effect. SERS spectra after mixing polyynes with silver colloids show a noticeable time evolution. Experimental results, supported by density functional theory (DFT) calculations of the Raman modes, allow us to investigate the behavior and stability of polyynes of different lengths and the overall sp conversion towards sp2 phase.
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 paper presents the results of investigation of the structure of porous condensates of Ag-NaCl and Cu-NaCl composition; chemical and phase compositions and dimensions of nanoparticles, produced from the vapour phase by EBPVD method. Silver and copper nanoparticles in a porous matrix, when removed from vacuum, oxidize in air to lower oxides, and have considerable sorption capacity relative to oxygen and moisture. Heating in air is accompanied by lowering of porous condensate mass, primarily, due to desorption of physically sorbed moisture, as well as afteroxidation to higher oxides due to ph…
The development of enhanced optical devices relies on key materials properties. In this context, researchers have investigated the effects of metal nanoparticles incorporation in active rare-earth materials. Here, we discuss the effects of Silver nitrate addition 0.5%, 1.0% and 2.0% mol%) into a Pr3+ doped tellurite-tungstate glasses (TWNN) formed by the conventional melt-quenching technique. The XRD curves confirmed the amorphous structural nature of TWNN glasses. The FTIR spectra identified the presence of different vibrational groups. DSC curves verified the increase around 70 oC for therma…
Metal nanoparticles have a substantial impact across different fields of science, such as photochemistry, energy conversion, and medicine. Among the commonly used nanoparticles, silver nanoparticles are of special interest due to their antibacterial properties and applications in sensing and catalysis. However, many of the methods used to synthesize silver nanoparticles often do not result in well-defined products, the main obstacles being high polydispersity or a lack of particle size tunability. We describe an automated approach to on-demand synthesis of adjustable particles with mean radii …
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…
In this work, ZnO nanowire arrays decorated with titanium nitride (TiN) nanoparticles as surface enhanced Raman scattering (SERS) substrates is demonstrated. ZnO nanowires were grown by hydrothermal synthesis while ~100 nm TiN nanoparticles were obtained by grinding commercial powders for several hours. They were then decorated on the ZnO nanowire arrays using acetone as the medium. Scanning electron microscopy confirmed the presence of TiN nanoparticles on the ZnO nanowires. TiN nanoparticles exhibited localized surface plasmon resonances at 430, 520 and 600 nm. SERS experiments using Nile Bl…
In this work, we report X-ray photoelectron (XPS) and valence band (VB) spectroscopy measurements of surfactant-free silver nanoparticles and silver/linear carbon chains (Ag@LCC) structures prepared by pulse laser ablation (PLA) in water. Our measurements demonstrate significant oxidation only on the surfaces of the silver nanoparticles with many covalent carbon-silver bonds but only negligible traces of carbon-oxygen bonds. Theoretical modeling also provides evidence of the formation of robust carbon-silver bonds between linear carbon chains and pure and partially oxidized silver surfaces. A …
This study utilizes molecular dynamics simulations to scrutinize the influence of type and volume fraction of nanoparticle on the density of nanofluids, i.e. silver (as a hydrophilic case) and titanium dioxide (as a hydrophobic case) water-based nanofluids. Ionic structure of TiO2 distinguishes the solid-liquid interactions with those in silver-water nanofluid. The thickness of nanolayer is estimated from density profile formed around the nanoparticle and is included in the density calculation. It is found that the type of interatomic potential between the nanoparticle and surrounding water ca…
Parity is a ubiquitous notion in science and serves as a fundamental principle for describing a physical system. Nanometer-scale metal objects are predicted to show dramatic differences in physical properties depending on the electron-number parity. However, the identification of the electron-number parity effects in real metal nanoparticles has remained elusive because of the variations in various features of nanoparticles. Here we report the nuclear magnetic resonance (NMR) detection of the dynamic effect of the electron-number parity in silver nanoparticles. With theoretical modeling of the…
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…
The present study reports on an innovative method to prepare discrete diamond nanoparticles or nanodiamonds (NDs) with high structural and optical quality through top-down approach by controlled oxidation of pre-synthesized nanocrystalline diamond (NCD) film. These NDs are studied for their structural and optical properties using atomic force microscopy (AFM), Raman and fluorescence (FL) spectroscopy. While AFM analysis confirms uniform distribution of discrete NDs with different sizes varying from a few tens of nanometers to about a micron, spectroscopic investigations reveal the presence of …
High quality InN nanoparticles are grown using atmospheric chemical vapour deposition technique via a self-seeded catalytic approach in the temperature range of 580 to 650 oC. In this temperature region, nucleation barrier of InN is overcome by seeding the low density In nano-particles prior to the introduction of reactive ammonia. Samples having increasing carrier density are grown with the help of increasing growth temperature to understand its role in optical phonon structure. Near resonance Raman spectra show complete different phonon pictures as compared to those for the off-resonance spe…
Recent Raman data on diamond and crystalline Si nanopowders are analyzed with the use of a microscopic theory of Raman scattering in ensembles of disordered nonpolar nanocrystals. The large width of the Raman peak in nanoparticles as compared to the corresponding peak in bulk materials and the peak inverse dependence on the particle size observed experimentally are explained within the framework of the theory. It is shown that this theory is capable to extract confidently from the Raman data four important microscopic characteristics of the nanopowder including the mean particle size, the vari…
Few inventions have shaped the world like the incandescent bulb. While Edison used thermal radiation from ohmically heated conductors, some noble metals exhibit "cold" electroluminescence (EL) in percolation films, tunnel diodes, electromigrated nanoparticle aggregates, optical antennae, or scanning-tunnelling microscopy (STM). The origin of this radiation, which is spectrally broad and depends on applied bias, is controversial given the low radiative yields of electronic transitions. Nanoparticle EL is particularly intriguing since it involves localized surface-plasmon resonances with large d…
Microscopic description of Raman spectra in nanopowders of nonpolar crystals is accomplished by developing the theory of disorder-induced broadening of optical vibrational eigenmodes. Analytical treatment of this problem is performed, and line shape and width are determined as functions of phonon quantum numbers, nanoparticle shape, size, and the strength of disorder. The results are found to be strongly dependent on either the broadened line is separated or it is overlapped with other lines of the spectrum. Three models of disorder, i.e. weak point-like impurities, weak smooth random potentia…
The programmable assembly of DNA strands is a promising tool for building tailored bottom-up nanostructures. Here, we present a plasmonic nanosystem obtained by the base-pairing mediated aggregation of gold nanoparticles (NPs) which are separately functionalized with two different single-stranded DNA chains. Their controlled assembly is mediated by a complementary DNA "bridge" sequence. We monitor the formation of DNA assembled NP aggregates in solution, and we study their Surface Enhanced Raman Scattering (SERS) response by comparison with the single NP constituents. We interpret the revealed…
