Electronic and fluorescence spectroscopy was used to show that the aggregation of rhodamine 6G molecules in a film-forming sol and derived hybrid films is a function of the equilibrium dye concentration and the micelle-forming agent and, as a consequence, the concentration of the micelle-forming agent in the film-forming sol affects the optical characteristics of the hybrid sol–gel films. Dye monomers were found to predominate in the sol, while the formation of nonplanar luminescent H-dimers is possible during film formation as a consequence of geometrical limitations of the dye molecules solubilized within the micelles.

Theoretical study of spontaneously emitted spectra of point-like source placed near spherical Ag particle was performed. It was shown that near-field electromagnetic interaction between a point-like emitter and spherical Ag particle leads to strong coupling between them at very small emitter-metal surface distances. It was shown that values of Rabi splitting are quantitatively close to that of emitter-flat substrate interaction.

The simultaneous measurement of Raman and fluorescence signals was proposed to find out the molecule-metal distance. The ratio between Raman and fluorescence intensities was used to estimate molecule-metal distance in nanometer scale. A low-value intensity of the fluorescence of the dye molecules was found using the photobleaching effect. Made was a comparison of experimental results with a theoretical model, which showed well agreement.

The authors report experimental studies of surface-enhanced Raman scattering (SERS) of wurtzite-type GaN and ZnO crystalline samples covered with Ag-nanoparticles. The longitudinal optical phonons consistently exhibit unusually intense Raman enhancement in comparison with other phonons. The anomaly is interpreted by a proposed model based on a resonant Raman scattering process assisted by metal-induced gap states at the Ag/GaN and Ag/ZnO interfaces. This study suggests that SERS of lattice vibrations in inorganic semiconductors is sensitive to their propagation nature, providing a progressive perspective view on electron-mediated enhanced Raman scattering.

We present a numerical study of the electric field enhancement in the immediate vicinity of the apex of a conical silver tip and show that an optimal cone angle exists, allowing one to maximize the electric field. This angle depends on the tip length, the wavelength, as well as on the distance from the apex to the observation point. So both the angle and length of the tip can be considered as parameters to adjust the peak enhancement resonant position for a laser source wavelength. At the same time, reducing the cone angle does not ensure a concurrent increase in the electric field enhancement. A simple qualitative interpretation is proposed to explain this phenomenon based on competition of two mechanisms affecting the electric field near the tip apex. The results obtained show that the point-like dipole approximation is invalid for description of the field enhancement of a finite-size metal tip in the case of scattering-type near-field optical microscopy. One more conclusion is that the model of a sharp semi-infinite perfectly conducting tip is also not adequate in our case.

Enhancement of the spontaneous decay rate due to local-field effects is estimated for a luminous dipole inside a small dielectric particle. To do this, we make use of an idea on multiplicativity of the local-field factor. Elongated particles are shown to be promising in respect of the local-field enhancement of the spontaneous emission. Computations are carried out within the framework of modern theory of the spontaneous decay of excited atoms in absorbing media for both the virtual-cavity and real-cavity models. Particular emphasis is placed on dielectric/semiconductor particles in the vicinity of the optical phonon frequencies.

We have applied the Lippmann-Schwinger equation to a corrugated dielectric film used as a scatterer. It was shown that the transmission and reflection spectra have sharp variations, when the wavelength corresponds to the excitation of the guided modes. The resonance line width is strongly increased with the corrugation. Double resonance is observed when only one film side is modulated.

We present a Raman scattering study for self-organized Ge dots on Si substrate. By means of difference Raman spectroscopy technique, we have separated the Raman signals from the Ge islands and Si substrate. The wetting layer thickness and strain were estimated from the line width and peak frequency. The estimated wetting layer thickness values are comparative with the Ge dot height obtained from microscopy measurements. The strain is decreased with an increase of the thickness.

The resonant light transmittance through opaque corrugated metal film with small radiation and absorption losses was studied numerically on the base of the Lippmann–Schwinger equation. It was found that the transmission coefficient reached its maximum at the surface plasmon resonance. The influence of the film’s geometry as well as of its dielectric properties on the light transmittance is discussed.

We present a Raman scattering study for self-organized Ge islands on Si substrate carried out at 10K. By means of difference Raman spectroscopy technique, we have separated the Raman signals from the Ge islands and Si substrate. The wetting layer thickness and strain were estimated from the line width and frequency peak. The estimated wetting layer thickness values are comparative with the Ge dot height obtained from microscopy measurements. The strain is decreased with an increase of the thickness.

We have measured the reflection spectra of ultra-thin InxGa1−xN/GaN layers on sapphire substrates with thick GaN buffer layer at temperatures of 300, 200 and 90K. We could not observe any signal associated with these layers. Comparing the measured spectra with the calculated ones for well-mixed InxGa1−xN layers, we concluded that our samples had no mixed state. We also concluded that the separated In and N atoms did not form InN layers. The reason for the fact that we did not observe a response from these layers is the inhomogeneous broadening of the InxGa1−xN reflection line. We have calculated the absorption spectra of small parallelepiped-like InN particles in the GaN matrix. It has shown that the absorption line width for such small parallelepiped-like particles is bigger than that for the bulk InN material. We concluded that our samples contained separated In and demonstrated formation of InN clusters.

Solving the self-consistent volume integral equation, we compute the local susceptibility, as well as volume-averaged one of a small parallelepipedal particle interacting with a flat substrate. To estimate the measure of nonpointness of a particle, the susceptibility in the particle center is compared with that calculated in the dipole point-like approximation. It is shown that a parameter specifying nonpointness is determined by the difference in the particle and ambient dielectric constant, as well as by measure of deviation of the particle shape from cubic one. Numerical calculations of absorption cross-section carried out for small dielectric (NaCl) particles show that the substrate effects lead to the low-frequency shift of the spectra and appearance of a low-frequency subsidiary peak.

In the work finding optical phonon energies from photoluminescence spectra and interpretation of their dependence on quantum well width are carried out. Remarkable decreasing both GaAs and AlAs phonon energies has been observed. It is shown that this dependence differs noticeably from that obtained from Raman spectra. The possible origin of this phenomenon is considered.

We consider a one-dimensional scattering problem and establish a system of two integral equations for the local (self-consistent) electric field. The equations are derived using the standard Green’s function method. Their solution yields the local fields at any point of the system. To illustrate the efficacy of this approach, we apply it to a film and obtain analytical solutions that are identical to the Fabry–Perot solution. Some potential applications of the approach are also discussed.

A Raman scattering study for self-organized Ge dots on Si substrate is presented. Raman signals from the Ge islands and Si substrate have been separated, by means of difference Raman spectroscopy technique. The wetting layer thickness and strain were estimated from the line width and the position of the peak. The estimated wetting layer thickness values are comparative with the Ge dot height obtained from microscopy measurements. As explained, the strain is observed to decrease with an increase of the Ge island height and the wetting layer thickness.

The thickness dependence of dielectric response of semicontinuous gold films evaporated onto glass substrates under various temperatures has been studied. A wide range of mass thicknesses (and filling factors) was considered, up to those corresponding to continuous films. The work includes a brief introduction, description of sample preparation and transmittance measurements, as well as determination of the dielectric response function using simple phenomenological model, namely, the generalized Bruggeman approximation. The approximation considers system's dimension as a varied noninteger quantity near the percolation threshold where the correlation length is large. The results obtained show that our model is valid in the actual range and dielectric properties of films are related to their morphological peculiarities. So, we refine and supplement some of our results reported in an earlier work (Proc. SPIE 3133 (1997) 300).

We performed the precision measurements of the near-normal far-infrared reflection and transmission spectra of the MBE-grown (GaAs)n/(AlAs)n (n= 1, 2, 4) superlattices. The results obtained show a noticeable (almost twofold) increase in the AlAs-phonon damping when n is decreased from 4 to 1. We consider possible physical mechanisms of this increase and compare our results with those obtained by other authors. The main implication of the work is that the increase in the TO-phonon damping may be related to interface broadening whose role becomes more important when the superlattice period decreases.

Granular gold and nickel films were prepared by thermal vacuum deposition onto glass substrates. Optical transmittance at near-normal incidence was recorded as a function of the relative mass thickness on each side of the percolation threshold. We show that our transmittance spectra may be described within the framework of Bruggeman's symmetrical approximation for the effective dielectric function with some modifications.