With examples of two parallel dielectric gratings and arrays thin cylinders, it is shown that the interaction between trapped electromagnetic modes can lead to scattering resonances with practically zero width. Such are bound states in radiation continuum first discovered quantum systems by von Neumann Wigner. Potential applications such photonic include: large amplification fields within structures and, hence, enhancement nonlinear phenomena, biosensing, as well perfect filters waveguides...

A fully quantum mechanical investigation using time-dependent density functional theory reveals that the field enhancement in a coupled nanoparticle dimer can be strongly affected by nonlinear effects. We show both classical as well linear descriptions of system fail even for moderate incident light intensities. An interparticle current resulting from strong photoemission tends to neutralize plasmon-induced surface charge densities on opposite sides junction. Thus, coupling between two...

The ability of localized surface plasmons to squeeze light and engineer nanoscale electromagnetic fields through electron-photon coupling at dimensions below the wavelength has turned plasmonics into a driving tool in variety technological applications, targeting novel more efficient optoelectronic processes. In this context, development active control plasmon excitations is major fundamental practical challenge. We propose mechanism for fast optical response metallic nanostructures based on...

Coupling molecular excitons and localized surface plasmons in hybrid nanostructures leads to appealing, tunable optical properties. In this respect, the knowledge about excitation dynamics of a quantum emitter close plasmonic nanoantenna is importance from fundamental practical points view. We address here effect excited electron tunneling into metallic nanoparticle(s) response. When nanoparticle, state on becomes short-lived because electronic coupling with metal conduction band states....

Finite temperature Car−Parrinello molecular dynamics simulations are performed for the protonated dialanine peptide in vacuo, relation to infrared multiphoton dissociation experiments. The emphasize flexibility of different torsional angles at room and dynamical exchange between conformers which were previously identified as stable 0 K. A proton transfer occurring spontaneously N-terminal side is also observed characterized. theoretical absorption spectrum computed from dipole time...

In plasmonic dimers, tunneling of electrons through the gap between nanoparticles is often seen as a major disadvantage due to quenching near fields associated it. Nevertheless, highly nonlinear process and thus it might be advantageous for certain applications. Using time-dependent density functional theory, authors investigate how second- third-harmonic generation influenced by electron in dimers. They show that currents ultranarrow gaps can strongly enhance high-harmonic generation.

The effect of an atomically thin Ar layer on the image-potential states Cu(100) surfaces is studied in a joint experimental-theoretical study, allowing detailed analysis interaction between surface electron and insulator layer. A microscopic theoretical description developed based mutually polarizing atoms. Account 3D structure allows one to predict energies lifetimes image excellent agreement with observations. layer, even as monolayer, efficiently insulating state from metal.

We show that periodic arrays of thin dielectric cylinders with constant higher than surrounding media can be used for an efficient second harmonic generation. The amplitude the reaches its absolute maximum when fundamental and fields are both in resonance trapped modes (quasistationary states) structure. It is shown double condition together phase matching generation achieved by a suitable choice array geometry. physical reason enhancement electromagnetic on at resonances, long interaction...

Using the tight binding description of electronic structure graphene and a time-dependent quantum approach, we address vibrational excitation molecules in near field nanoantenna. The possibility tuning plasmon frequency by electrostatic doping allows an efficient resonant infrared (IR)-active modes via coupling between molecular dipole field. We show that for carbon monoxide CO placed gap dimer antenna formed 20 nm size patches, υ=1←0 transition leads to distinct signature IR absorption...

Vibrational excitation by low-energy electron impact of ${\mathrm{N}}_{2}$ molecules physisorbed on rare-gas films is studied both experimentally and theoretically in the energy range ${\mathrm{N}}_{2}^{\mathrm{\ensuremath{-}}}$ ${(}^{2}{\ensuremath{\Pi}}_{g})$ resonance. The experimental measurements provide dependence vibrational (i.e., function) overtone ratio for solid Ar with thickness varying between 1 32 monolayers condensed a Pt substrate. oscillations function ``boomerang''...

The nonlinear response of metallic nanoparticles is obtained from quantum time dependent density functional theory calculations. Without any aprioristic assumption our calculations allow us to identify high-order harmonic generation in canonical plasmonic structures such as spherical single particles and dimers. Furthermore, we demonstrate that under currently available experimental conditions, the application an external polarizing field allows actively control even-order otherwise symmetry...

The electron impact excitation of a molecule located inside dielectric medium is theoretically studied. Electronic an ${\mathrm{O}}_{2}$ embedded in pieces Ne fcc crystal variable size calculated. described using microscopic model. structures that appear the energy dependence inelastic scattering probabilities are related to electronic properties host medium. They assigned either bulk or quantization effects finite cluster. In present case, probability shown directly reflect density states.

We address the possibility of atomic-scale control plasmon modes graphene nanostructures. Using time-dependent many-body approach we show that for zigzag and armchair nanoribbons, single carbon atom vacancy results in ``on'' ``off'' switching longitudinal or a change their frequency. The effect stems from robust underlying physical mechanism based on strong scattering two-dimensional (2D) electrons defects lattice. Thus our findings establish platform optical response engineering sensing 2D...

The exceptional electronic and optical properties of graphene are harmed by the unavoidable imperfections lattice resulting from mechanical or interaction with environment. Using a time-dependent approach, we theoretically address sensitivity plasmon modes nanoflakes to presence point vacancy defects substitutional impurities. We find that fractions as low 10–3 total number carbon atoms in an ideal nanoflake lead strong broadening resonance absorption spectrum. In addition this effect...

We use a time-dependent density functional theory approach to study the optical response of hybrid nanostructure where junction between thin metallic films is functionalized with quantum well (QW) structure. show that an unoccupied QW-localized electronic state opens possibility active electrical control photoassisted electron transport through and absorption at frequencies. Control strategies based on applied bias or external THz field are demonstrated.

We use classical electrodynamics, time-dependent density functional theory, and random-phase approximation to study the gap plasmons propagating in nm-wide between metal surfaces. Particular emphasis is given quantum effects emerging when junction functionalized with a nanostructure supporting unoccupied localized electronic states. With example of well (QW) introduced we show that optically assisted electron transport across via gateway QW states might strongly affect lifetime propagation...

Plasmonic nanostructures are able to strongly enhance and localize electromagnetic radiation. In particular, dimer configurations can light into the plasmonic gap very effectively greatly increase field enhancement due excitation of bonding dipole plasmon (BDP)[1]. The strong allows induce nonlinear processes using less powerful sources [2], so that dimers be a useful physical system build optoelectronic devices. It is thus desirable perform rigorous theoretical studies responses such...