Substrates for enhancing the giant Raman signal (SERS) of light are being actively developed for the purpose of accurate detection of low concentrations of organic molecules. However, the complexity and high cost of fabricating substrates often limit their application. A simple method for obtaining SERS substrates based on nanoporous glass functionalized by means of silver particles is proposed, and the efficiency of the substrates in detecting low concentrations of benzoic acid is demonstrated.

We study the silica gel-glasses obtained by vitrification in air or in a gas mixture of H 2 :Ar xerogels doped with Sm, Al, and Ba. It is found that during their synthesis it is possible to form impurity hexagonal and tetragonal crystallites of SiO 2 and tetragonal crystallites of SmSi 2 . When the reducing synthesis conditions are applied, the incorporation of samarium in glass simultaneously in two oxidation states (3+ and 2+) takes place. Meanwhile, Sm-Al-containing glasses provide a sufficiently effective sensitization of the luminescence of Sm 2+ ions by Sm 3+ ions, while in Sm-Al-Ва-containing glasses this effect is absent because Sm 2+ ions are localized mainly in the glass sublattice formed with the participation of Ba 2+ ions. Based on the spectra obtained, the positions of the energy states of the Sm 2+ and Sm 3+ ions in such glasses are calculated.

The fifth author's name should read K. N. Nishchev. Figure 3 on page 587 is incorrect.

Physics, Chemistry and Application of Nanostructures, pp. 287-290 (2017) No AccessSTRUCTURAL AND LUMINESCENT PROPERTIES OF YAl3(BO3)4:Ce3+,Tb3+ POLYCRYSTALS SYNTHESIZED BY COLLOID CHEMICAL APPROACHESG. P. Shevchenko, Y. V. Bokshits, Y. U. Ivlieva, G. V. Shishko, T. G. Khottchenkova, G. E. Malashkevich and I. I. SergeevG. P. ShevchenkoResearch Institute for Physical Chemical Problems, Belarusian State University Leningradskaya 14, 220030 Minsk, Belarus, Y. V. BokshitsResearch Institute for Physical Chemical Problems, Belarusian State University Leningradskaya 14, 220030 Minsk, Belarus, Y. U. IvlievaResearch Institute for Physical Chemical Problems, Belarusian State University Leningradskaya 14, 220030 Minsk, Belarus, G. V. ShishkoResearch Institute for Physical Chemical Problems, Belarusian State University Leningradskaya 14, 220030 Minsk, Belarus, T. G. KhottchenkovaB. I. Stepanov Institute of Physics NASB, Nezavisimosti Ave. 68, 220072 Minsk, Belarus, G. E. MalashkevichB. I. Stepanov Institute of Physics NASB, Nezavisimosti Ave. 68, 220072 Minsk, Belarus and I. I. SergeevB. I. Stepanov Institute of Physics NASB, Nezavisimosti Ave. 68, 220072 Minsk, Belarushttps://doi.org/10.1142/9789813224537_0066Cited by:0 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail Abstract: Polycrystalline phosphors of yttrium aluminum borates YAl3(BO3)4 activated with Tb3+ ions and co-activated with Ce3+ ions were synthesized by colloid chemical approaches: co-precipitation of hydroxides from corresponding salts aqueous solutions in the presence of boric acid with a subsequent heat treatment. Their phase composition, morphology and luminescence were investigated. The intensity of luminescence of the Tb3+ under UV excitation (λexc = 310 nm) is increased by two orders of magnitude for samples co-activated with Ce3+ and Tb3+ ions. That indicates the effective sensitization of Tb3+ luminescence by Ce3+ ions. FiguresReferencesRelatedDetails Physics, Chemistry and Application of NanostructuresMetrics History PDF download

Y 3 Al 5 O 12 :Ce 3+ ceramics additionally doped with chromium from the gas phase were synthesized by a colloidchemical method. It was established that its luminescence spectrum included a broad poorly resolved band with a barycenter at 570 nm due to Ce 3+ and narrow bands in the region 670–750 nm due to Cr 3+ in Y 3 Al 5 O 12 and YAlO 3 . The structure of Cr 3+ optical centers in both subsystems, the kinetic properties of their luminescence, and the transfer between them of electron excitations were considered.

It is shown that glasses in the system (Ln x Y1 – x )2O3O3–Al2O3–B2O3 are a promising matrix for obtaining highly doped active media with low-efficiency concentration quenching of luminescence. However, because high-frequency vibrational oscillators [BO3] present in such glasses it is preferable to use activators with an energy gap between a metastable state and a lower state above 8000 cm–1 closest to it.

Glass and products of solid-phase synthesis in the form of samarium-activated single-phase powders with huntite structure were obtained in the system Y 2 O 3 –Al 2 O 3 –B 2 O 3 . It was shown that the glasses studied crystallize with predominately aluminum borate Al 4 B 2 O 9 precipitating in the bulk and the solid solution (Y, Sm)Al 3 (BO 3 ) 4 on the surface of the sample. When the crystalline powders (Sm x Y 1 – x )Al 3 (BO 3 ) 4 transitioned into an amorphous state leveling of the Stark structure and broadening of the luminescence bands of Sm 3+ was observed, but the luminescence branching ratios changed very little. It was found that lowering the synthesis temperature of such glasses from 1450 to 1250°C increases the BO 4 fraction and quantum yield of luminescence with low activator concentration.

The concentration dependence of the quantum yield of luminescence of Tm 3+ ions in an oxychloride matrix has been measured in individual bands of their luminescence excited at different wavelengths. The concentration dependences of the quantum yield of luminescence were calculated with allowance for the effect of the unintentional impurity of rare-earth ions. The cross-relaxation nature of the concentration dependence of the rare-earth ion luminescence is discussed.

We investigated the luminescence characteristics of Tm3+ ions depending on their concentration in an oxychloride matrix. We measured luminescence spectra, luminescence excitation spectra, concentration dependences of the intensity and kinetics of various luminescence bands of rare‐earth ions of the visible and IR ranges at different excitation wavelengths. We carried out calculations of the concentration dependences of the quantum yield of luminescence: total and individual spectral bands. The cross‐relaxational nature of concentration effects in the luminescence of rare‐earth ions is discussed.

In order to raise the efficiency of cryogenic refrigerators and liquefiers, it is very important to replace the JT process, which involves large losses of exergy, by the improved process of adiabatic expansion. This paper presents test results of the second-generation wet turboexpander for the Nuclotron helium refrigerators. A rotor is fixed vertically by a combination of gas and hydrostatic oil bearings. The turbines are capable to operate at a speed of 300,000 revolutions per minute. The power generated by the turbine goes into friction in the oil bearings. The design of the new wet turboexpander was executed in view of those specific conditions, which arise due to the operation at liquid helium temperature. The application of this new expansion machine increases the efficiency of the Nuclotron helium refrigerators by 25 %.

The concentration and temperature dependences of the blue luminescence intensity of the Tm 3+ ion in yttrium oxide under UV and IR excitation have been measured. We made a proposal that the main role in the formation of these dependences is played by the interionic cross relaxation of excited states of Tm 3+ ; the presence of admixed secondary rare‐earth ions can strongly influence the shape of the temperature dependence of the anti‐Stokes luminescence intensity, displacing the position of its maximum. It is shown that the quenching action of admixtures under Stokes and anti‐Stokes excitation shows up differently because of the differences in the mechanisms of population of the luminescent level.