Influence of the Local Field and Dipole-Dipole Interactions on the Spectral Characteristics of Simple Metals and Their Nanoparticles

The effect of dipole-dipole interactions of free electrons on the spectral characteristics of simple metals and their nanoparticles is analyzed using Drude theory and the model of the Lorentz local field. It is established that accounting for the dispersion of a local field under conditions of one-dimensional (1D) confinement based on the optical constants of the bulk metal allows the determination of its spectral micro-characteristics in the frequency region of the longitudinal collective motions of the free electrons. This corresponds to the spectra of the dielectric losses of bulk plasma oscillations. A similar procedure for three-dimensional (3D) confinement produces the spectrum of dielectric losses at the frequency of localized plasma oscillations. Using a number of simple metal examples, viz., Li, Na, and K, and also Al, Be, and Mg, it is shown that the frequencies of volume and localized plasma oscillations obtained from a model of dispersion of the local field in the long-wave limit are in good agreement with the actual frequencies of the plasma oscillations of the corresponding metals and the absorption maxima of their nanoparticles with a radius of 2–20 nm. It is shown that the frequencies of the main mode of longitudinal plasma oscillations and the absorption frequency of localized plasmons are well described using the dynamic theory of crystal lattice vibrations

Обнаружение золотистого бычка Gobius xanthocephalus (Gobiidae) в районе юго-восточного побережья Крыма (Чёрное море)

Приведены сведения об обнаружении золотистого бычка Gobius xanthocephalus Heymer & Zander, 1992 (Gobiidae, Perciformes) в районе юго-восточного побережья Крыма (Чёрное море), где ранее данный вид не находили. Особь этого вида отмечена при проведении подводных ихтиологических исследований в акватории Двуякорной бухты, у северо-восточной оконечности полуострова Киик-Атлама (44°57′ с. ш., 35°23′ в. д.). Бычок зарегистрирован на глубине 8,5 м у подножия подводной части скалистого склона, в затенённой нише среди скопления глыб. Обнаружение золотистого бычка в районе Юго-Восточного Крыма свидетельствует о расширении его ареала в полигалинных акваториях северной части Чёрного моря

The Size Ellect on the Infrared Spectra of Condensed Media Under Conditions of ID, 2D and 3D Dielectric Confinement

A general expression for the dielectric loss spectrum of an absorbing composite medium was obtained from a Maxwell-Garnett general equation. This expression was simplified for the cases of one, two and three dimensional dielectric confinement in both ordered and disordered thin layers, rods (wires) and spheres of absorbing medium which are considered as mesoparticles or mesoscopic molecules. This theoretical approach was verified experimentally using high purity organic liquids with strong absorption bands in the infrared range. Three organic liquids, namely benzene, chloroform and carbon disulphide, were measured in various dielectric confinement configurations using Fourier Transform Infrared (FTIR) spectroscopy with a Grazing Angle attachment GATRTM. A significant shift of the resonant absorption band of liquid mesoparticles was observed for various dielectric confinement geometries which is in good agreement with theoretical predictions. Possible applications of this work include investigations of industrial smoke, toxic aerosols and liquid droplets

Study of Structure and Quality of Different Silicon Oxides Using FTIR and Raman Microscopy

In this work, SiO2 and fluorine and phosphorous doped SiO2 thin films are investigated using FTIR and Raman techniques. FTIR spectroscopy was performed at normal and oblique incidence of the probe beam in transmission and reflection modes. The effect of polarisation and angle of incidence of the probe beam is examined for the case of reflection mode. Infrared spectra taken from doped oxides show that the structure changes with the passage of time. Alternate methods to calculate the thickness of the doped film are therefore discussed. Infrared spectra of electron beam evaporated oxides give valuable information on their structure and water content. The porosity is calculated for these samples. Finally, micro-Raman spectroscopy is used to measure the fluorine content in a device structure

The Effect of the Internal Field on the IR Absorption Spectra of Small Particles in Case of 3D, 2D and 1D Size Confinement

The spectral properties of composite materials based on small particles under 1D, 2D, and 3D size confinement are described using a combination of dispersive internal field and effective media theory approaches. Calculations performed for a number of crystalline materials have shown that the peak position and intensity of the vibrational band of the material under conditions of 1D, 2D, and 3D size confinement are changed, whereas the bandwidth of the band remains the same. In the case of 3D confinement, the peak position of the spectrum of isolated “mesoparticles” ( ) appears to be very close to the intrinsic frequency of the lattice vibrations, calculated from the elastic constants of this crystal, as well as to the Fröhlich\u27s frequency. The largest shift (Δν) of the peak frequency, νmax, from the bulk value is obtained in the case of 1D confinement when the peak position is practically coincident with the frequency of the longitudinal optical phonon (νLO). These shifts are the result of intermolecular interactions, including both resonant and induced resonant dipole−dipole interactions