Alina Manshina

Er3+ to glass matrix energy transfer in Ga–Ge–S:Er3+ system

Abstract Spectroscopic characteristics (spontaneous emission probabilities, radiative lifetimes, oscillator strengths, branching ratios and quantum efficiency) of Er 3+ in Ga 2 S 3 –GeS 2 –Er 2 S 3 glassy system are investigated by use of Judd–Ofelt theory. Lifetime measurements 4 S 3/2 level of Er 3+ in Ga 2 S 3 –GeS 2 –Er 2 S 3 glasses with various Er 3+ concentrations and optical gap energy are performed. Estimations of the non-radiative relaxation rate and the multiphonon relaxation rate demonstrate the occurrence of energy transfer from Er 3+ ion to the electronic states of the glass matrix. The way of the practical application of this non-radiative energy transfer is suggested.

Up-conversion fluorescence in Er-doped chalcogenide glasses based on GeS2-Ga2S3 system

Abstract The up-conversion fluorescence excited with 813 and 1550 nm light is investigated in glasses of the Ga2S3–GeS2–Er2S3 system. The influence of the glassy matrix composition and Er concentration on the luminescence and absorption spectra is studied. Increasing the Ga content relative to Ge decreases the erbium concentration quenching effect. The efficiency of up-conversion fluorescence has a strong dependence on thermal history of the sample. Annealing of the glasses and decreasing the synthesis temperature increase the luminescence intensity.

Photoluminescence properties of Eu3+ ions in yttrium oxide nanoparticles: defect vs. normal sites

The position of activator ions in the lattice has a fundamental effect on the luminescent properties of phosphors. In this paper, we describe the normal and defect sites of Eu3+ ions in a Y2O3 crystal lattice, their interaction and difference in physical properties. Analytically detectable amounts of defect sites reached in Y2O3:Eu3+ nanopowders with an average size of 40–50 nm were synthesized by a novel combined Pechini-foaming method. The luminescence properties of Eu3+ ions in defect sites are most pronounced in highly doped nanocrystalline powders (32 and 40 at%). To explain this phenomenon we suggest the mechanism of irreversible energy transfer from normal to defect sites of Eu3+ ions.

Laser-induced transformation of supramolecular complexes: approach to controlled formation of hybrid multi-yolk-shell Au-Ag@a-C:H nanostructures.

In the present work an efficient approach of the controlled formation of hybrid Au–Ag–C nanostructures based on laser-induced transformation of organometallic supramolecular cluster compound is suggested. Herein the one-step process of the laser-induced synthesis of hybrid multi-yolk-shell Au-Ag@a-C:H nanoparticles which are bimetallic gold-silver subnanoclusters dispersed in nanospheres of amorphous hydrogenated a-C:H carbon is reported in details. It has been demonstrated that variation of the experimental parameters such as type of the organometallic precursor, solvent, deposition geometry and duration of laser irradiation allows directed control of nanoparticles’ dimension and morphology. The mechanism of Au-Ag@a-C:H nanoparticles formation is suggested: the photo-excitation of the precursor molecule through metal-to-ligand charge transfer followed by rupture of metallophilic bonds, transformation of the cluster core including red-ox intramolecular reaction and aggregation of heterometallic species that results in the hybrid metal/carbon nanoparticles with multi-yolk-shell architecture formation. It has been found that the nanoparticles obtained can be efficiently used for the Surface-Enhanced Raman Spectroscopy label-free detection of human serum albumin in low concentration solution.

Laser-induced synthesis of metallic silver-gold nanoparticles encapsulated in carbon nanospheres for surface-enhanced Raman spectroscopy and toxins detection

Metallic silver-gold nanoparticles (1–5 nm) encapsulated into carbon nanospheres (20–30 nm) were synthesized via laser-induced chemical liquid phase deposition. The obtained carbon-silver-gold nanostructures were characterized by high specific surface area and demonstrated high sensitivity as a material for surface-enhanced Raman scattering and adsorption properties allowing analyte extraction from a dilute solution for quantitative monitoring of low concentration components.

Hybrid nanostructures: synthesis, morphology and functional properties

Hybrid nanostructures representing combinations of different materials and possessing properties that are absent in separate components forming the hybrid are discussed. Particular attention is given to hybrid structures containing plasmonic and magnetic nanoparticles, methods of their synthesis and the relationship between the composition, structure and properties. The functional features of the hybrid nanomaterials of various morphology (with core?shell structures, with encapsulated metal nanoparticles and with metal nanoparticles on the surface) are considered. The unique properties of these hybrid materials are demonstrated, which are of interest for solving problems of catalysis and photocatalysis, detecting impurities in various media, in vivo visualization, bioanalysis, as well as for the design of optical labels and multifunctional diagnostic nanoplatforms. The bibliography includes 182 references.

Direct laser writing of μ-chips based on hybrid C–Au–Ag nanoparticles for express analysis of hazardous and biological substances

Micro-chips based on organic-inorganic hybrid nanoparticles (NPs) composed of nanoalloys of gold (Au) and silver (Ag) embedded in an amorphous carbonaceous matrix (C-Au-Ag NPs) were prepared directly on a substrate by the laser-induced deposition (for short: LID) method. The C-Au-Ag NPs show a unique plasmon resonance which enhances Raman scattering of analytes, making the μ-chips suitable to detect ultra-low-volumes (10(-12) liter) and concentrations (10(-9) M) of bio-agents and a hazardous compound. These micro-chips constitute a novel, flexible solid-state device that can be used for applications in point-of-care diagnostics, consumer electronics, homeland security and environmental monitoring.

Glasses of the Ga2S3-GeS2 system doped with rare-earth ions (Nd3+,Er3+) as active optical materials

Physical-chemical and optical properties of glassy system Ga-Ge-S, doped with Nd3+, Er3+ were treated from viewpoints of differential-temperature analysis, Raman and luminescence spectroscopy. Strong correlation between network structure and luminescence efficiency of Ga-Ge-S:Nd, Er system is established. Increase of Ga2S3 contents in Ga-Ge-S:Nd, Er system leads to forming of ternary structure units and enhances luminescence efficiency.

Laser-induced deposition of hetero-metallic structures from liquid phase

Laser-induced chemical-liquid phase deposition of hetero-metallic (Gu-Cr) structures is demonstrated for the first time. The deposition of hetero-metallic structures is of special interest thanks to wider range of properties as compared to pure metals. The deposition was realized from the electrolyte solution based on copper sulphate and potassium dichromate. The focused beam of the continuous wave Ar+ laser generated in the multiwave regime was used for the structures precipitation. The chemical processes resulting in Cu-Cr structures deposition are analyzed emphasizing some features typical for laser-assisted methods.

Single-longitudinal-mode linear-cavity fiber laser using multiple subring-cavities

A single-longitudinal-mode selection is realized in a linear-cavity fiber laser construction using a loop-back optical circulator and a partial reflectance fiber Bragg grating as the cavity ends. At 1551 nm wavelength, the measured signal-to-noise-ratio is 56 dB and with a line width less than 1 MHz obtained using multiple subring cavities as mode filters. The pumping efficiency is 10% improved by recycling the residual pump power to gain medium.