Optical Properties and Upconversion Luminescence of BaTiO Xerogel Structures Doped with Erbium and Ytterbium.

Erbium upconversion (UC) photoluminescence (PL) from sol-gel derived barium titanate (BaTiO:Er) xerogel structures fabricated on silicon, glass or fused silica substrates has been studied. Under continuous-wave excitation at 980 nm and nanosecond pulsed excitation at 980 and 1540 nm, the fabricated structures demonstrate room temperature PL with several bands at 410, 523, 546, 658, 800 and 830 nm, corresponding to the H → I, H → I, S → I, F→ I and I→ I transitions of Er ions. The intensity of erbium UC PL increases when an additional macroporous layer of strontium titanate is used beneath the BaTiO xerogel layer.

Detection of explosives in vapor phase by field asymmetric ion mobility spectrometry with dopant-assisted laser ionization.

Detection of low-volatile explosives in concentrations below 10 g/cm is a great challenge for portable ion mobility spectrometers (IMS) and field asymmetric IMS (FAIMS). We study the capabilities of FAIMS detector with ultraviolet laser ionization combined with organic additives (dopants) toluene and 1-methylnaphtalene to sense nitro-explosives: trinitrotoluene (TNT) and low-volatile cyclonite (RDX) and nitropentaerythritol (PETN). Differential mobility coefficients were measured for target ion peaks of TNT, RDX and PETN.

Laser-stimulated desorption of organic molecules from surfaces, as a method of increasing the efficiency of ion mobility spectrometry analysis.

Application of laser-induced desorption was investigated as a method of increasing the efficiency of gas phase analyzers on principles of field asymmetric ion mobility spectrometry. Mass spectrometric data of investigations of laser desorption of pentaerythritoltetranitrate molecules and cyclotetramethylenetetranitramine molecules from quartz substrate under vacuum were obtained. Laser sources a Nd:YAG with nanosecond pulse duration (λ = 532 nm) and a continuous wave diode laser (λ = 440 nm) were used.

Active sampling system for gas-phase analyzers.

The approaches for increasing a contact-free sampling distance up to 40 cm for a field asymmetric ion mobility spectrometer were investigated and implemented by use both the vortex flow made by a rotating impeller and the laser desorption of traces of low volatile explosives. The sampling device for a laser-based field asymmetric ion mobility spectrometer including a high-speed rotating impeller was designed and built with help of computer simulation of vortex and analytical flows. The dependence of a signal of trinitrotoluene vapors on a rotational speed of an impeller was obtained.

Controlled influence of quantum dots on purple membranes at interfaces.

The development of bio-sensitized nanofilms engineered from biomembrane components and inorganic nanoparticles is a promising field of colloid and interface science and technologies. Recent nano-bioengineering approaches employing quantum dots (QDs) permit the enhancement of the purple membrane (PM) "light-harvesting capacity" compared to native PMs. The influence of QDs on the PM properties, especially the bacteriorhodopsin (bR) photocycle, has been found that has both fundamental (mechanisms of photoreception) and applied implications (including the fabrication of hybrid bionanomaterials).

The photophysics of porous silicon: technological and biomedical implications.

Although porous silicon (pSi) was first obtained in the mid-20th century, considerable interest in this material arose much later, due to the discovery of its room-temperature photoluminescence (PL). In the 1990s, most studies on pSi were focused on the analysis and explanation of its photoluminescent and electroluminescent characteristics and their potential practical applications. The latest advances in pSi research are related to its biocompatibility and biomedical applications.