Ag Cylinder Research Articles

A Coupled‐Dipolar Plasmonic Antenna for Enhanced and Directional Emission from a Single NV Center at the Generalized Kerker Condition

AbstractPlasmonic antennas are widely used to achieve substantial emission rate enhancement. These antennas suffer from significant absorption losses that preclude the observation of Kerker conditions in such systems. The perfect balancing of the Mie‐scattering moments in an antenna at the generalized Kerker condition provides radiation directionality to its far‐field scattering pattern and zero absorption losses, a situation not achievable for a plasmonic system. Here, using both theoretical and computational approaches, the superposition of Mie‐scattering moments induced by coupling two individual silver (Ag) cylinders in a coupled‐dipolar plasmonic antenna is discussed. This results in the balancing of multipolar moments to a large extent with unidirectional scattering and hence the generalized Kerker condition in a plasmonic system. By placing a nanodiamond‐based single NV‐ center in the plasmonic gap‐cavity formed between the two Ag cylinders, >300 times Purcell enhancement is achieved with improved emission directionality leading to 80% collection efficiency. The proposed coupled‐dipolar plasmonic antenna is well suited for generating bright single photon emissions with a GHz emission rate, which is helpful for quantum photonic applications.

Using multi-polar scattering and near-field plasmonic resonances to achieve optimal emission enhancement from quantum emitters embedded in dielectric pillars

Recently, high refractive index micro-pillars have been widely used for enhancing the fluorescence of quantum emitters (vacancy/defect centers) embedded within the pillar. However, the maximum observed enhancement from these pillars has been limited to about a factor of 10. Within the dielectric pillars, the Purcell enhancement is restricted to around unity, and the fluorescence enhancement is mainly due to the enhancement of the collection efficiency of the dipole emission from inside the pillar if compared to a bulk substrate. Using multi-polar electromagnetic scattering resonances and near-field plasmonic field enhancement/confinement, here we report a simple metal–dielectric pillar resonator scheme to achieve a close to three orders of magnitude fluorescence enhancement from embedded solid state vacancy centers. The scheme comprises a silver (Ag) cylinder fabricated on top of a silicon-carbide (SiC) dielectric pillar, with both the SiC and Ag cylinders having the same diameter. A selective dipole orientation relative to the metal–dielectric interface for emitters close to the SiC pillar’s top surface leads to a large Purcell enhancement of the dipole’s emission. The Ag cylinder was found to function as an efficient resonator as well as an antenna, enhancing as well as directing a significant fraction of the dipole’s emission into far-field free space.

Coupling of Quantum-Well Excitons to Plasmons in One-Dimensional Metal Nanocylinder Gratings

Theory of plasmon-exciton coupling is developed for a metal nanocylinder grating located in the vicinity of a semiconductor quantum well. In dipole approximation, the effective polarizability of cylinders is derived, taking into account generation of quantum-well excitons in the near field of surface plasmons. Given the polarizability, the spectra of reflection and absorption are calculated for metal-semiconductor systems to study the effect of plasmon-exciton interaction. The excitonic response is shown to be enhanced by high-quality plasmons of Ag cylinders, although strong coupling is not attained for realistic nanostructure parameters.

Structural Phase Transition of AgOx Sandwiched Between ZnS–SiO2 Protective Layers Under Thermal and Laser Pulse Annealing for Super-Resolution Near-Field Recording

The as-deposited AgOx prepared at an oxygen flow ratio of 0.5 consisted of Ag2O and AgO phases. During thermal annealing, the reduction of AgO into Ag2O, decomposition of Ag2O into Ag and O2, and out diffusion and aggregation of decomposed Ag would take place successively. The chemical decomposition of AgOx film sandwiched between two ZnS–SiO2 protective layers was confirmed to be an irreversible process. As being irradiated by a high power laser pulse similar to the recording process, a hollow Ag cylinder, or ring, serving as an aperture, was formed in the AgOx mask layer, and small Ag particles, serving as light-scattering centers, were precipitated in the center region. During the readout process, the small aperture can significantly reduce the readout laser spot size, while the strong near-field interaction between precipitated Ag particles and sub-wavelength marks can effectively enhance the readout signal. That elucidates the recording and readout mechanisms of super-resolution near-field structure disk with an AgOx mask layer.

Effect of constituent phases of reactively sputtered AgOx film on recording and readout mechanisms of super-resolution near-field structure disk

We have studied the dependence of the constituent phases of reactively sputtered AgOx mask layer on the recording and readout mechanisms of super-resolution near-field disk. At low oxygen flow ratios, the AgOx mask layer was found to be composed of an appreciable amount of Ag particles with sizes of tens of nanometers and Ag2O phase. After recording by a high power laser pulse, a hollow Ag cylinder that had its center filled with O2 was formed in the AgOx mask layer. The hollow Ag cylinder would serve as an aperture and could effectively reduce the laser spot size during readout, leading to the super-resolution effect only. At high oxygen flow ratios, the AgOx mask layer was found to be mostly composed of Ag2O and/or AgO phases. After recording by a high power laser pulse, a hollow Ag cylinder that had its center filled with nanosized Ag particles was formed in the AgOx mask layer. The nanosized Ag precipitates would serve as light-scattering centers and could yield strong near-field interaction with the subwavelength marks, resulting in both the super-resolution and near-field effects during readout.

Recording and readout mechanisms of super-resolution near-field structure disk with a silver oxide mask layer

The chemical decomposition of AgOx sandwiched between two ZnS–SiO2 protective layers was an irreversible process. We confirmed that a hollow Ag cylinder, or ring, serving as an aperture, was formed and small Ag particles were precipitated in the center region during the recording process. The small aperture can significantly reduce the laser spot size during the readout process and the strong near-field interaction between precipitated Ag particles and subwavelength marks can effectively enhance the readout signal. That clarifies both the super-resolution effect and the near-field interaction in the super-resolution near-field structure disk.

Nanoparticle Optics: The Importance of Radiative Dipole Coupling in Two-Dimensional Nanoparticle Arrays

In this paper, the electromagnetic interactions between noble metal nanoparticles are studied by measuring the extinction spectra of two-dimensional arrays of Au and Ag cylinders and trigonal prisms that have been fabricated with electron beam lithography. The nanoparticles are typically 200 nm in diameter and 35 nm in height; both hexagonal and square array patterns have been considered with lattice spacings that vary from 230 to 500 nm. The extinction spectra typically have a maximum in the 700−800 nm region of the spectrum, and this maximum blue shifts as lattice spacing is reduced, having typically a 40 nm decrease in λmax for a 100 nm decrease in lattice spacing. The results are similar for the different noble metals, array patterns, and nanoparticle shapes. The extinction spectra have been modeled using coupled dipole calculations, and the observed spectral variations are in good qualitative agreement with experimental data. Moreover, the computational analysis indicates that the blue shifts are due...

Frequency modulation in the transmittivity of wave guides in elastic-wave band-gap materials.

It is shown, for the first time, that the transmittivity of wave guides created as rectilinear defects in periodic elastic band-gap materials oscillates as a function of frequency. The results are obtained using the finite difference time domain method for elastic waves propagating in two-dimensional inhomogeneous media. The oscillations of the transmittivity are due to the richness of modes in the elastic systems and, mainly, due to the periodicity of the potential in the direction of the wave propagation. Results are presented for a periodic array of Pb and Ag cylinders inserted in an epoxy host, as well as for Hg cylinders in an Al host.

Quantum oscillations in superconductors in magnetic field

The Aharonov–Bohm oscillations (ABO) of the free energy, the critical temperature, and the magnetic susceptibility in a stack of hollow mesoscopic cylinders are calculated. It is shown that sinusoidal (in flux) ABO crosses over to the parabolic Little–Parks oscillations (LPO) when the diameter of cylinders exceeds the coherence length. The exponential temperature behaviour of the magnetic susceptibility is like that found in Ag cylinders with thin Nb coating [Czech. J. Physics 46 (1996) 2317]. The formal analogy between oscillations of the free energy in the Aharonov–Bohm system in question and the de Haas–van Alphen oscillations (dHvAO) in layered superconductors is discussed.

Quantum-coherent phenomena in mesoscopic proximity structures

We have investigated the magnetic response of a Ag cylinder in proximity with Nb at 300 μK≤T≤9K and in the very clean limit. Below a temperature at which the proximity decay length ξN=ℏvF/2πkBT becomes of the order of the perimeterL (σN∼-0.2L), we observe a reentrance of the induced diamagnetic susceptibility χd. The reentrant susceptibility χr follows χr=Aexp(-T/T* withT*=ℏvF/2πkBL. AtT=T*, where σN=L, the logarithmic slope of χr becomes steeper by a factor of 2 so that forT<T*, a new, stronger mesoscopic regime is reached with χr=Bexp(-2T/T*).

Tailormade: [formula omitted], first lithooxoiridate

We obtained previously unknown K 3{Li[IrO 4]} in the form of dark-red elongated single crystals, by heating well-ground mixtures of Li 2IrO 3 and KO 0.51 (molar proportions Ir:K, 1.00:3.76) in an “Ag cylinder” (at 1073 K for 71 days). K 3{Li[IrO 4]} crystallizes as mC36 in the space group C2/ c, with a = 1067.29(9) pm, b = 986.36(8) pm, c = 587.70(5) pm and β = 103.938(8)°; Z = 4. Refinement of the structure with 949 reflections ( F 0 > 3 σ( F 0)) from 1032 independent reflections (merged from 4137 I 0( hkl)) gave R = 0.0351 and R w = 0.0378. The structure is characterized by Vierer single chains ∞ 1[(O 2 2 LiO 2IrO 2 2 ) 2] isolated from one another. Their arrangement corresponds to the configuration of a densest packing of “tree-trunks”. The effective coordination numbers, mean fictive ionic radii and the Madelung part of the lattice energy, as well as the charge distribution are calculated and discussed.

Ein neues Oxomanganat(V) mit Elpasolith-Variante: (KNa)K[MnO 4

(KNa)K[MnO 4] has been prepared for the first time as blue-green orthorhombic single crystals by heating mixtures of the appropriate oxides (K 2O 2, Na 2O 2 and LiMnO 4; K:Na:Mn=1.2:1.3:1; Ag cylinder; 580 °C, 66 days). The structure determination (four-circle diffractometer; Mo Kα; for all 618 I o( hkl) R=10.2% and R w =3.8%; space group Fddd (no. 70) confirms the presence of an unusual elpasolith variation corresponding to (KNa)K[MnO 4]. Guinier-Simon data gave a=1044.4(2) pm; b=1126.0(3) pm; c=1698.9(3) pm; Z=16. The Madelung part of the lattice energy MAPLE and the effective coordination numbers ECoN, derived from the mean fictive ionic radii MEFIR, together with the charge distribution are calculated and discussed.

Glucose enzyme electrode with percutaneous interface which operates independently of dissolved oxygen.

An enzyme glucose electrode that operates even when no oxygen is dissolved in the glucose solution has been developed and its in vitro performance evaluated. The electrode has been designed to be used with a percutaneous interface for future in vivo use. Oxygen is supplied to the electrode from the atmosphere. The electrode is based on the conventional H2O2 detecting enzyme electrode, in which an Ag cylinder 4.5 mm in diameter and 16 mm in length is used as a cathode. A Pt wire 0.5 mm in diameter is fixed in the centre for an anode, and 0.5 micrograms of albumin-linked glucose oxidase is immobilised at the tip of the anode. A recess of 3.6 mm diameter and 5 mm depth is made at the top of the electrode, and a breathing orifice 0.8 mm in diameter is drilled along the axis of the electrode to link the recess to the atmosphere. A thin oxygen permeable silicone layer fills the recess, allowing oxygen in the atmosphere to be supplied to the enzyme through the silicone layer. The electrode has a linear response to glucose concentration at an electrode output current ranging from 0 to 20 nA even when the oxygen concentration of the glucose solution is zero. The use of polyurethane as a diffusion barrier to glucose limits the electrode output current at a glucose concentration of 500 mg dl-1 (27.8 mmol 1-1] to 20 nA. Therefore, the electrode can measure glucose concentrations up to 500 mg dl-1 (27.8 mmol 1(-1] with no oxygen dissolved in the glucose solution. The electrode with the percutaneous interface seems suitable for implantation in sites of low oxygen concentration such as subcutaneous tissues.

ChemInform Abstract: The First Oxogallate with Chains of Tetrahedra.

AbstractK2Na4(GaO3)2 has been prepared by annealing a mixture of the binary oxides (K:Na:Ga = 4.4:2.2:1, Ag cylinder, 600 °C, 25 d).

ChemInform Abstract: A New Oxocadmate with Blocks of Tetrahedrons, Cs14Cd9O16,

Abstracthas been prepared as pale yellow single crystals by annealing an intimate mixture of CdO and CsO0.47 (Cs:Cd = 1.5‐2.2:1.0, Ag cylinder, 500 °C, 20 d).

ChemInform Abstract: New Metal Oxides with Double Tetrahedra as Building Units: Rb6(Tl2O6) and Cs6(In2O6)

Abstractare prepared as single crystals by annealing intimate mixtures of Tl2O3 and RbO0.60 (Rb:Tl = 3.5:1) or In2O3 and CsO0.53 (Cs:In = 3.5:1) in a closed Ag cylinder at 650 °C for 14 d. The compounds are isotypic and crystallize in the monoclinic crystal system, space group P21/a, Z=2.

ChemInform Abstract: A New Oxoiridate(V): KLi6[IrO6

AbstractDark red single crystals of the title compound are obtained by annealing a mixture of K4[IrO4] and LizO at 750°C for 30 d (Ag cylinder, vacuum).

ChemInform Abstract: The First Oxoaurate(I) with Dumb‐bell‐like Anion: KNa2(AuO2).

AbstractTransparent light yellow single crystals of the title compound have been prepared by annealing a mixture of NaAu, Na2O2, and K202; (221 :l) at 430°C for 6d (sealed Ag cylinder).

ChemInform Abstract: Novel Synthetic Routes to Metal Oxides: Na3TlO2 from NaTl and Na2O2.

AbstractNaTl reacts with Na2O2 in a closed Ag cylinder (580°C, 14d) to give yellow single crystals of the novel oxide Na3TlO2.

Ein neues kationenreiches Oxogallat Zur Kenntnis von K2Li3GaO4/A New Cation Rich Oxogallate About K2Li3GaO4

Abstract The new compound K2Li3GaO4 was prepared from binary oxides (powder) and from LiGaO2/KO0.48 (colourless transparent single crystals) in a closed Ag cylinder at 600 °C. It crystallizes in the monoclinic space group P21/c with the constants a = 553.6(2) 6 = 880.4(3) c = 1093.1(4) pm β = 111.52(3)°. Z = 4, drö = 3.017 and dpyk = 2.97 g·cm-3 . [4-circle diffractometer data, 1333 I0 (hkl), Mo-Ka, R = 4.95 and Rw = 5.04%, anisotropic refinement.] The new structure type is complicated. The characteristical features are shown using Schlegel projections of the coordination polyhedrons. Extended Schlegel Diagrams, a novel application of graph theory, are used. They describe bijective how the coordination polyhedra are three-dimensionally combined.