In the second-order Raman spectra of ceramic solid solutions, LiNb_xTa_1−xO₃ weak overtone bands of fully symmetric fundamental polar excitations were observed for the first time. The frequencies of the two bands exceeded the value of the overtone frequency corresponding to the fully symmetrical vibration 4A₁(z). The possibility of the existence of phonon bound states of the antipolar type in the vibrational spectrum of LiNb_xTa_1−xO₃ ceramics is predicted.

We propose two convenient methods to quickly detect the presence of non-milk fat (palm oil) in butter, as well as to determine its amount in the product. For the first time, we have experimentally obtained the dependence of the size of drops of an alcoholic emulsion of oil or spread on the content of palm oil in it by the dynamic light scattering (DLS) method. We have also obtained the dependence of intensity ratio of the components of spread luminescence spectrum on palm oil content when excited at a wavelength λ = 266 nm. These results allowed us to propose two methods for determining the adulteration of butter with palm oil using DLS and measuring luminescence spectra. The two methods are physically independent but successfully supplement each other. DLS and luminescent methods for determining the proportion of palm oil give errors of no more than 10% and 6%, respectively.

Raman scattering (RS) spectra in lithium tantalate single crystals are studied at 180-degree scattering geometry in a wide frequency spectral range (50R

The results of a study of the structural perfection of crystals and ceramics of lithium niobate and lithium tantalate of various compositions are presented. In solid solutions of the LiNbxTa1-xO3 family with 0.4 ≤ x ≤ 0.6, lines were found in the Raman spectra, both of the first (in the range of 150–900 cm–1) and of the second order, located in the range of 900–2000 cm–1. Second-order Raman lines in the range 900–2000 cm–1 were also recorded by us in single crystals of single-doped lithium niobate and lithium tantalate LiNbO3:Tb (2.24 wt. %), LiTaO3:Cr (0.005 wt. %), and double-doped lithium tantalate LiTaO3:Cr (0.2):Nd (0.45 wt. %). The observed lines in the range 900–2000 cm-1 are explained as a manifestation of overtone processes corresponding to biphonons.

It was found that resonant two-photon-excited luminescence is observed in zinc-phosphate optical glass doped with sodium uranate with a concentration of 2.

Fluorescence emission-excitation matrices for cow milk samples with different fat contents in the range of 0.05–10% and a constant protein content of 3%, as well as for butter and extracted milk components such as casein and lactose, have been measured using a spectrofluorometer. The influence of the increased fat content on the shape of the fluorescence spectra of milk has been studied. In addition, fluorescence spectra measured for serial dilutions of high-fat milk with water and skim milk, along with aqueous dilutions of skim milk, have shown that the fluorescence diagnostics of fat and protein content in milk can be implemented using excitation at only two wavelengths: 280 and 320 nm. The optimal spectral ranges proposed for detecting the content of milk components via fluorescence measurements can be useful when designing UV LED-based fluorescence analyzers of milk composition.