The luminescence spectra of a microresonator structure consisting of a spherical core of small diameter (3.5-6 mcm) covered with a luminescent shell with a refractive index less than that of the core are modeled. Shell luminescence spectra, radial distribution of the whispering gallery mode (WGM) field, and mode parameters (wavelength, width, quality factor) are calculated using the expansion of the electromagnetic wave field in the basis of vector spherical harmonics and the method of spherical wave transfer matrices. The dependence of the luminescence spectra and WGM parameters on the geometric and optical parameters of the structure --- the shell thickness, the refractive index of the shell, and the core diameter --- is studied. Keywords: spherical microresonator, luminescent shell, whispering gallery modes, modeling of luminescence spectra.

We have investigated the formation of microparticles-based Coulomb crystals in a linear vertical quadrupole Paul trap with a single end-cap electrode. For the first time, we have described the effect of gravity on Coulomb crystals formation. We have observed a new type of stable Coulomb crystals configuration that we referred to as "Christmas tree-like Coulomb crystals". We have provided numerical simulation and experimental research of the "Christmas tree-like Coulomb crystals" and discussed these structures in the perspective of Science and Art performance.

The effect of the thickness and refractive index of the shell on the amplitudes of lines of the TE and TM polarized whispering gallery modes (WGMs) in the emission spectrum of a microcavity structure consisting of a spherical core covered with a luminescent shell with a refractive index greater than that of the core is studied. The luminescence spectra of the shell, the radial distribution of the WGM field, and the mode parameters (wavelength, quality factor, and effective volume) are calculated using the method of spherical wave transfer matrices. It is shown that at certain subwavelength shell thicknesses, the amplitude of the TE mode emission peak is many times greater than the amplitude of the TM mode peak with the same polar, azimuthal, and radial indices. This is explained by the fact that with these parameters of the shell, WGMs propagate inside the shell as waveguide modes.

Luminescent hybrid spherical microresonators of two types consisting of monodisperse spherical silica particles with a diameter of 3.5 μm coated with either FITC dye molecules or a 200 nm thick mesoporous silica shell containing DCM dye are fabricated. The luminescence spectra of microresonators are studied and the experimental emission spectra are simulated using the method of spherical wave transfer matrices. The ratio of intensities of emission lines into whispering gallery modes with different polarizations and the same polar and radial indices is analyzed. It is shown that the ratio depends on the orientation of the dipole moment of the radiative transition of dye molecules relative to the surface of spherical silica particles. Keywords: spherical microresonator, whispering gallery modes, organic dyes, photoluminescence.

Submicron spherical silica particles were synthesized via base hydrolysis of tetraethoxysilane (TEOS) and phenyltriethoxysilane (PTEOS) in a presence of cetyltrimethylammonium bromide. It was shown that the replacement of a part of TEOS with PTEOS in the reaction mixture led to formation of particles containing hierarchical micro-mesoporous structure with specific surface area of up to similar to 1170 m(2) g(-1). The amount of PTEOS leads to the increase of water contact angle of the particles from 10 degrees to 155 degrees which causes a gradual change in their surface properties from hydrophilic to superhydrophobic. The static adsorption capacity of the particles was measured for water, toluene and methyl isobutyl ketone and was found to be affected by both the amount of OH- or C6H5-groups on the surface and the characteristics of porosity. In particular, the adsorption capacity for non-polar volatile organics increases with the increase of the hydrophobicity of particles. It was found that synthesized superhydrophobic silica particles efficiently and quickly absorb oil from water surface and then can be easily removed mechanically.

Luminescent hybrid spherical microresonators of two types consisting of monodisperse spherical silica particles with a diameter of 3.5 mcm coated with either FITC dye molecules or a 200 nm thick mesoporous silica shell containing DCM dye are fabricated. The luminescence spectra of microresonators are studied and the experimental emission spectra are simulated using the method of spherical wave transfer matrices. The ratio of intensities of emission lines into whispering gallery modes with different polarizations and the same polar and radial indices is analyzed. It is shown that the ratio depends on the orientation of the dipole moment of the radiative transition of dye molecules relative to the surface of spherical silica particles.

The effect of the thickness and refractive index of the shell on the amplitudes of lines of the TE and TM polarized whispering gallery modes (WGMs) in the emission spectrum of a microcavity structure consisting of a spherical core covered with a luminescent shell with a refractive index greater than that of the core is studied. The luminescence spectra of the shell, the radial distribution of the WGM field, and the mode parameters (wavelength, quality factor, and effective volume) are calculated using the method of spherical wave transfer matrices. It is shown that at certain subwavelength shell thicknesses, the amplitude of the TE mode emission peak is many times greater than the amplitude of the TM mode peak with the same polar, azimuthal, and radial indices. This is explained by the fact that with these parameters of the shell, WGMs propagate inside the shell as waveguide modes.

Monodisperse carbon nanodots modified with europium ions possessing photoluminescence in the entire visible region of the spectrum were synthesized by the template method. The chemical composition and structure of the resulting white nanoluminophore were studied by X-ray spectral and microscopic methods.

Monodisperse molybdenum-disulfide nanoparticles are synthesized in the mesopores of a template, i.e., spherical silica ( m SiO 2 ) particles. First, the pores of the m SiO 2 particles are impregnated with the precursor (ammonium tetrathiomolybdate) solution. Then, MoS 2 is synthesized from the precursor within the pores of m SiO 2 via the annealing of particles in a H 2 S/H 2 atmosphere under thermodynamically equilibrium conditions. To obtain individual MoS 2 nanoparticles, the template material ( a -SiO 2 ) is selectively removed from the composite m SiO 2 /MoS 2 particles via etching in HF. The average size of the MoS 2 nanoparticles is determined by microscopic methods to be 3.5 nm. According to dynamic light scattering data, the nanoparticles have a low root-mean-square size scatter (18%).

The template method was used to synthesize monodisperse carbon nanodots modified with europium ions and exhibiting photoluminescence in the entire visible spectral range. The chemical composition and structure of the obtained white nanoluminophore were studied by X-ray spectral and microscopic methods.

Spherical multiporous silica nanoparticles (MPSNs) with the diameter of 50 ± 15 nm containing two types of nanopores with the sizes of 0.8–2 nm (type I) and 5–10 nm (type II) inside are synthesized. The film formed from MPSNs contains pores with the size of 10–40 nm (type III) formed due to the packaging of spherical nanoparticles. Methods for the selective introduction of dye molecules of propidium iodide (PI), carbon nanodots (CDs) with the size of 3.5 nm, and Ag nanoparticles (20 nm) into pores of types I, II, and III, respectively, are developed. The possibility of using MPSN/CD and MPSN/CD/Ag films as luminophores for white light LEDs is shown. It is demonstrated that composite particles of MPSN/CD and MPSN/CD/PI are nontoxic and allow visualization of the cell structure (by the example of HeLa) simultaneously in several spectral ranges.

Magneto-optical effects in metal–dielectric nanostructured materials based on opal films coated with a thin cobalt/silver nanolayer, whose surface has a close-packed hexagonal lattice of metal nanohemispheres and nanoholes, have been investigated. It has been demonstrated experimentally and theoretically that a wide spectrum of modes of propagating surface plasmon polaritons is excited in such a system, which leads to a resonant enhancement of the magneto-optical effect in the Voigt geometry.

The luminescence spectra of a microresonator structure consisting of a spherical core of small diameter (3.5 – 6 mcm) covered with a luminescent shell with a refractive index less than that of the core are modeled. Shell luminescence spectra, radial distribution of the whispering gallery mode (WGM) field, and mode parameters (wavelength, width, quality factor) are calculated using the expansion of the electromagnetic wave field in the basis of vector spherical harmonics and the method of spherical wave transfer matrices. The dependence of the luminescence spectra and WGM parameters on the geometric and optical parameters of the structure - the shell thickness, the refractive index of the shell, and the core diameter - is studied.

Plasmonic structures are extremely attractive for the light flow manipulation. In turn, the spectrum of the plasmon excitations can be controlled by external magnetic field, thus giving rise to magnetoplasmonics. However, in the case of traditional magnetoplasmonic structures, the enhancement of magneto-optical (MO) effects is often accompanied by the transmission damp, which constricts the area of their applications. This paper examines resonant optical effects in composite structures based on artificial opal films covered by a thin cobalt layer, which forms a 2D hexagonal lattice of nanoholes in the metal film. Such periodic structure exhibits surface plasmon polariton-assisted extraordinary transmission along with the increase of odd in magnetization intensity magnetooptical effect in the Voigt geometry. Local field enhancement accompanying the surface plasmon polaritons excitation in composite Co/opal structure provides a distinct enhancement of the magnetization-induced second harmonic generation (SHG) and relevant MO effects at the SHG wavelength that appear as Fano-type resonances. High transmission along with resonantly-high MO effects make Co/opal films promising in plasmonic applications.

Исследованы магнитооптические эффекты в металл-диэлектрических наноструктурированных материалах на основе пленок опала, покрытых тонкой пленкой кобальт/серебро, поверхность которых представляет собой плотноупакованные гексагональные решетки металлических нанополусфер и наноотверстий. Экспериментально и теоретически показано, что в такой системе возбуждается широкий спектр мод бегущих поверхностных плазмон-поляритонов, что приводит к резонансному усилению магнитооптического эффекта в геометрии Войта.

The influence of the parameters of exciting radiation and temperature on the spectral characteristics of the narrow photoluminescence lines of nanodiamonds obtained by chemical vapor deposition is studied. It is shown that the ratio of line intensities in the spectrum depends on the wavelength and the power of the exciting radiation. For some lines, with increasing power, there was also observed a shift in the position of their maximum and broadening. Changes in the relative intensity of the lines occurred after irradiation of nanodiamonds with a laser beam with a power density of about 1.2 × 105 W/cm2. With an increase in temperature in the range of 79–300 K, a temperature damping of their intensity is observed.

Monodisperse molybdenum disulfide nanoparticles were synthesized in mesopores of spherical silica particles (mSiO2) served as a template. First, the pores of mSiO2 particles were impregnated with the precursor (ammonium tetrathiomolybdate solution). Then, the reduction of the filler in thermodynamically equilibrium conditions in H2S/H2 atmosphere was carried out. The template material (a-SiO2) was selectively etched from the composite mSiO2/MoS2 particles with HF to obtain individual MoS2 nanoparticles. The mean size of MoS2 nanoparticles determined by microscopic methods was found to be 3.5 nm. According to dynamic light scattering data, the nanoparticles had low size scatter (18%).

Spherical multiporous silica nanoparticles (MSNPs) with a diameter of 50 ± 15 nm containing two types of nanopores with sizes of 0.8–2 nm (type I) and 5–10 nm (type II) are synthesized. The film formed from MSNPs contains pores 10–40 nm in size (type III) as a result of spherical nanoparticles packing. Methods are developed for the selective introduction of dye molecules – propidium iodide (PI), carbon nanodots (CD) 3.5 nm in size, and Ag nanoparticles (20 nm) into pores of types I, II, and III, respectively. The possibility of using MSNP/CD and MSNP/CD/Ag films as phosphors for white light LEDs is demonstrated. It is shown that composite MSNP/CD and MSNP/CD/PI particles are non-toxic and allow visualization of the cell structure (by the example of HeLa) simultaneously in several spectral ranges.

The influence of the excitation parameters and temperature on the spectral characteristics of narrow photoluminescence lines in nanodiamonds obtained by chemical vapor deposition is investigated. It is shown that the ratio of the line intensities in the spectrum depends on the wavelength and power of the excitation radiation. For some lines, with increasing power, a shift in the position of their maximum and broadening is also observed. After irradiation of nanodiamonds with a laser beam with a power density of ~1.2·105 W/cm2, the relative line intensities change. With increasing temperature in the range 79 - 300 K, temperature quenching of their intensity is observed.

Hybrid structures were synthesized from monodisperse spherical silica particles, which are spherical microcavities, and emitting carbon nanodots on their surface. Carbon nanodots are attached to the surface of the particles by controlled coagulation in three solvents: ammonia, hydrochloric acid and glycerol. Intense narrow lines associated with the emission of nanodots in the whispering gallery modes of a spherical microcavity were observed in the photoluminescence spectra of hybrid structures over the entire radiation wavelength range of carbon nanodots from UV to near IR. All observed lines were identified by comparison with the spectral positions of the whispering gallery modes calculated by the method of spherical wave transfer matrices.