We demonstrate the transition from isolated to collective optical modes in plasmonic oligomers. Specifically, we investigate resonant behavior of planar hexamers and heptamers with gradually decreasing interparticle gap separation. A pronounced Fano resonance is observed heptamer for separations smaller than 60 nm. The spectral characteristics change drastically upon removal central nanoparticle. Our work paves road toward complex hierarchical oligmers tailored properties.

Future photonic circuits with the capability of high-speed data processing at optical frequencies will rely on implementation efficient emitters and detectors nanoscale. Towards this goal, bridging size mismatch between radiation subwavelength or by nanoantennas is a subject current research in field plasmonics. Here we introduce an array three-dimensional Yagi–Uda antennas, fabricated using top-down fabrication techniques combined layer-by-layer processing. We show that concepts...

We study the near-field optical behavior of Fabry-Pérot resonances in thin metal nanowires, also referred to as quasi one-dimensional plasmonic nanoantennas. From eigenmodes well beyond quadrupolar order we extract both, propagation constant and reflection phase guided surface plasmon polariton with superb accuracy. The combined symmetry breaking effects oblique illumination retardation allow excitation dipole forbidden, even resonances. All measurements are supported by rigorous simulations...

We present a comprehensive experimental study of the optical properties plasmonic oligomers. show that both constitution and configuration oligomers have large influence on their resonant behavior, which draws compelling analogy to molecular theory in chemistry. To elucidate influence, we vary size individual nanoparticles identify role target nanoparticle from spectral change. illustrate positions numbers oligomer. Additionally, demonstrate experimentally redshift at transition displaced...

Recent advances in nanolithography have allowed shifting of the resonance frequency antennas into optical and visible wavelength range with potential applications, for example, single molecule spectroscopy by fluorescence directionality enhancement molecules. Despite such great promise, analytical means to describe properties is still lacking. As phase velocity currents at frequencies metals much below speed light, standard radio (RF) antenna theory does not apply directly. For fundamental...

We map in real space and by purely optical means near-field information of localized surface plasmon polariton (LSPP) resonances excited nanoscopic particles. demonstrate that careful polarization control enables apertureless scanning microscopy (aSNOM) to image dipolar quadrupolar LSPPs the bare sample with high fidelity both amplitude phase. This establishes a routine method for situ plasmonic other resonant structures under ambient conditions.

Plasmonic nanoantennas are versatile tools for coherently controlling and directing light on the nanoscale. For these antennas, current fabrication techniques such as electron beam lithography (EBL) or focused ion (FIB) milling with Ga+-ions routinely achieve feature sizes in 10 nm range. However, they suffer increasingly from inherent limitations when a precision of single nanometers down to atomic length scales is required, where exciting quantum mechanical effects expected affect...

Plasmonics has become one of the most vibrant areas in research with technological innovations impacting fields from telecommunications to medicine. Many fascinating applications plasmonic nanostructures employ electric dipole and higher-order multipole resonances. Also magnetic resonances are recognized for their unique properties. Besides these multipolar modes that easily radiate into free space, other types electromagnetic exist, so-called toroidal eigenmodes, which have been largely...

Hyperbolic media exhibit unparalleld properties, e.g, as light absorbers in photovoltaics and photonics, superlenses far-field imaging, subwavelength concentrators nanolithography, or novel materials emission engineering. With the advent of optical metamaterials, deliberate design material properties became possible. However, inadvertent variability fabrication techniques other factors limit performance characteristics man-made hyperbolic materials. Here, we draw attention to a class natural...

Nanoantennas confine electromagnetic fields at visible and infrared wavelengths to volumes of only a few cubic nanometres. Assessing their near-field distribution offers fundamental insight into light-matter coupling is special interest for applications such as radiation engineering, attomolar sensing nonlinear optics. Most experimental approaches measure near-fields employ either diffraction-limited far-field methods or intricate scanning techniques. Here, using diffraction-unlimited...

We present near-field measurements of optical Yagi-Uda nanoantennas that are used in receiving mode. The eigenmode imaging amplitude and phase by apertureless scanning microscopy allows us to investigate the dynamics local out-of-plane electric field components visualize temporal evolution this time-harmonic reception process. antenna directionality manifests itself dependence enhancement at feed element on illumination direction. Simulations taking into account substrate confirm our...

We report on the interplay between strong coupling and radiative damping of strongly coupled excitons (Xs) surface plasmon polaritons (SPPs) in a hybrid system made J-aggregates metal nanostructures. The optical response is probed at field level by angle-resolved spectral interferometry. show that two different energy transfer channels coexist: coherent resonant dipole-dipole interaction an incoherent exchange due to spontaneous emissions photon one emitter its subsequent reabsorption...

The effects of zero-point motion and the anharmonicity lattice vibrations diamond have been explored theoretically in context a valence force model explicitly incorporating isotopic composition. predictions are tested study elastic moduli (${\mathit{c}}_{\mathit{ij}}$) deduced from Brillouin spectra zone center optical mode frequency (${\mathrm{\ensuremath{\omega}}}_{0}$) Raman isotopically controlled specimens. On basis parameter associated with bond stretching, comparison theory...

We report on the implementation of a versatile dynamic mode apertureless scanning near field optical microscope (aSNOM) for nanoscopic investigations properties at surfaces and interfaces. The newly developed modular aSNOM optomechanical unit is essentially integrable with multitude laser sources, homemade probe microscopes (SPMs) as well commercially available SPMs demonstrated here. instrument especially designed to image opaque without restriction transparent substrates. In description we...

The ion beam deposition (IBD) of rhodamine dye molecules on solid surfaces in high vacuum is explored order to characterize the possibility fabricating molecular coatings or nanostructures from nonvolatile molecules. Molecular beams with a well-defined composition are deposited silicon oxide controlled kinetic energy. Photoluminescence spectroscopy and time-of-flight secondary mass spectrometry (TOF-SIMS) employed sample respect coverage, homogeneity, fraction intact landed ions...

Using energy-filtered transmission electron microscopy we measured surface-plasmon resonances of gold nanoplatelets with different shapes and edge lengths at high spatial resolution. We find equidistant maxima the energy-loss probability along platelet edges. The plasmon dispersion geometries is very similar, i.e., hardly dependent on specimen shape. experimental results are verified by means finite-difference time-domain calculations which reveal presence wedge-plasmon polaritons...

We report the observation of coherent light scattering from nanometer-sized gap regions in a nanofocusing scanning near-field optical microscope. When approaching gold taper to surface thin semitransparent film and detecting transmission, we find steep increase intensity over last 5 nm signal selected k-space. This is confirmed as signature highly confined plasmons by detailed comparisons finite element method simulations. The simulations reveal that confinement adjustable via underlying...

We demonstrate that the spin-orbit coupling of two-dimensional surface states can be detected locally by scanning-tunneling spectroscopy (STS). The spin splitting state induces a singularity in local density which as distinct peak differential conductance spectrum. From STS spectrum we determine Rashba energy measure strength splitting. Its detection and imaging are demonstrated for alloys Bi Pb on Ag(111), exhibit particularly large spin-split band structures. influence surface-state...

Resonant nanoplasmonic structures have long been recognized for their unique applications in subwavelength control of light enhanced transmission, focussing, field confinement, decay rate management, etc. Increasingly, they are also integrated electro-optical analytical sensors, shrinking the active volume while at same time improving sensitivity and specificity. The microscopic imaging resonances such dynamic variations has seen dramatic advances recent years. In this Minireview we outline...

We investigate the optical modes in three-dimensional single-crystalline gold tapers by means of electron energy-loss spectroscopy. At very proximity to apex, a broad-band excitation at all photon energies from 0.75 2 eV, which is onset for interband transitions, detected. large distances though, we observe distinct resonances with energy dispersions roughly proportional inverse local radius. The nature these phenomena unraveled finite difference time-domain simulations taper and an...

The quantum dynamics of the two-dimensional image-potential states in front Cu(100) surface is measured by scanning tunneling microscopy and spectroscopy. dispersion relation momentum resolved phase-relaxation time first state are determined from interference patterns local density at step edges. It demonstrated that tip-induced Stark shift does not affect motion electrons parallel to surface.

Using Brillouin scattering, we have determined the complete set of elastic constants technologically important β-Si3N4. Availability single crystals has allowed us to measure all five independent cij, which (in units GPa) are: c11=433(3), c33=574(3), c13=127(5), c44=108(2), c66=119(4), and c12=c11−2c66=195(8), giving a bulk modulus 259. Our values are compared with existing calculations cij from nano-indentation results combined empirical relations trends in related materials.

We investigate the local optical response of split-ring resonator-(SRR)-based metamaterials with an apertureless scanning near-field microscope. By mapping near fields suitably resonant micrometer-sized SRRs in near-infrared spectral region uncoated silicon tip, we obtain a spatial resolution better than lambda/50. The experimental results confirm numerical predictions excitations SRRs. Combining studies near- and far-field simulations provides detailed understanding resonance mechanisms...

By energy-filtering transmission electron microscopy (EFTEM), we observe Fabry-Pérot-like surface plasmon resonances (SPRs) along the length of rectangular single and double slits drilled into free-standing thin silver films. These eigenmodes hybridize in closely situated slits. The nature their lateral coupling is uncovered from finite-element simulations, which show that symmetry energy sequence hybrid modes governed by Babinet complementarity principles. Interestingly, a slit system,...

The coupling of atmospheric pressure ionization (API) sources like electrospray (ESI) to vacuum based applications mass spectrometry (MS) or ion beam deposition (IBD) is done by differential pumping, starting with a capillary pinhole inlet. Because its low transfer efficiency the inlet represents major bottleneck for these applications. Here we present nano-ESI interface optimized exploit hydrodynamic drag background gas collimation and reduction space charge repulsion. Up limit 40 nA...