Sealed-off commercial active elements of metal-vapor lasers with output power in the range 1–50 W

Designs and output characteristics of sealed-off active elements (AE) ofCu-andAu-vapor lasers with output power in the range 1–50 W are given. State Scientific-Production Enterprise “Istok”. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 67–73, August, 1999.     

Analysis of regularization processes in an ensemble of coupled chaotic oscillators

We study how the collective dynamics of an ensemble of active coupled elements depends on the number of connections between them. We use Chua’s nonlinear oscillators as elements of this ensemble and assume nonlinear coupling. Regularization and suppression of oscillations in the transition from global to local coupling are examined. This work was presented at the Summer Workshop “Dynamic Days” (Nizhny Novgorod, June 30–July 2, 1998). Lobachevsky State University of Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 12, pp. 1558–1564, December, 1998.     

Comparison of selected optical properties of oxyfluoride glass fibers doped with Er3+ and co-doped with Er3+ Yb3+

The method of manufacturing and spectroscopic evaluation of the Er³⁺ ions doped and Er³⁺–Yb³⁺co-doped SiO₂–Al₂O₃–Na₂CO₃–CaO–PbO–PbF₂ oxyfluoride glass fibers is presented in the paper. Both optically active elements erbium and ytterbium were introduced into the batch in the form of fluorides. The X-ray diffraction (XRD) technique was applied at each stage of fibers manufacturing in order to control an amorphous structure of the preforms and fibers. Optical studies of glass preforms and fibers (reflection/transmission, absorption, emission, and excited state absorption (ESA)) were directed to examine their suitability as fiber amplifiers at 1.55 μm band.     

Calculation of the characteristics of a two-mode laser with weakly coulped anisotropic cavities

On the basis of the method of self-consistent waves in lasers with weakly coupled anisotropic cavities we obtained analytical expressions for the spectrum of radiation frequencies and threshold gain coefficients of orthogonally polarized waves in the active part of a coupled cavity for an arbitrary set of anisotropic and other optical elements in its passive part. Belarusian State Polytechnic Academy, 65, F. Skorina Ave., Minsk, 220027, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 2, pp. 262–265, March–April, 1999.     

Experimental measurement of effective atomic number of composite materials for Compton effect in the <Emphasis Type="Italic">γ</Emphasis>-ray region 280–1115 keV by a new method

In this paper, we report a new method to determine the effective atomic number, Z _eff, of composite materials for Compton effect in the γ-ray region 280–1115 keV based on the theoretically obtained Klein–Nishina scattering cross-sections in the angular range 50°–100° as well as a method to experimentally measure differential incoherent (Compton) scattering cross-sections in this angular range. The method was employed to evaluate Z _eff for different inorganic compounds containing elements in the range Z = 1–56, at three scattering angles 60°, 80° and 100° at three incident gamma energies 279.1 keV, 661.6 keV and 1115.5 keV and we have verified this method to be an appropriate method. Interestingly, the Z _eff values so obtained for the inorganic compounds were found to be equal to the total number of electrons present in the sample as given by the atomic number of the elements constituting the sample in accordance with the chemical formula of the sample. This was the case at all the three energies.     

Method of detecting rare superheavy nuclei decay events—the active correlation technique

Recently, a successful cycle of experiments on the synthesis of superheavy elements with Z = 112–118 has been accomplished with ⁴⁸Ca beam at the Flerov Laboratory of Nuclear Reactions (FLNR), JINR. From the viewpoint of detection of rare decay and background suppression this success was achieved owing to a new radical technique, the method of active correlations. It employs the search in a real-time mode for a pointer to probable correlation like recoil-alpha for switching the beam off. In the case of detection in the same detector strip an additional alpha-decay event of the “beam OFF” time interval is automatically prolonged. Reasonable scenarios of developing the method are considered.     

Calculation of energy characteristics for Si<Subscript>1–<Emphasis Type="Italic">x</Emphasis></Subscript>Ge<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>–Si structures with single quantum wells

Energy characteristics of Si_1–x Ge _x –Si quantum-size structures with single quantum wells were calculated numerically based on a four-band k·p method. Analytical expressions for the Luttinger parameters are obtained as functions of the component composition of Si_1–x Ge _x compounds. Analytical expressions for the energy ħω of optical band-to-band transitions are obtained in an effective mass approximation and agree well with numerical calculations by the k·p method. This allows one to determine accurately a range of changes while varying the component compositions and thickness of the active and barrier layers.     

The study of the bolometric response of detector elements based on nanostructured HTSC-films

The bolometric response of detector elements based on nanostructured films BiSr–Ca–Cu–O is studied after 10 years of storage in natural conditions. The thermal relaxation of bolometers is measured at a low duty ratio of optical pulses in a frequency range of 1–10 kHz.     

Nonlinearities in the reflection and transmission spectra of the photonic bandgap heterostructures with n–i–p–i crystals

Nonlinear optical properties of photonic crystal heterostructures with embedded n–i–p–i superlattices are investigated. Self-consistent calculations of the transmission and reflection spectra near the defect mode are performed using the transfer-matrix method and taking into account the gain saturation. Analysis of features and output characteristics is carried out for one-dimensional photonic crystal heterostructure amplifiers in the GaAs–GaInP system having at the central part an active “defect” from doubled GaAs n–i–p–i crystal layers. The gain saturation in the active layers in the vicinity of the defect changes the index contrast of the photonic structure and makes worse the emission at the defect mode. Spectral bistability effect, which can be exhibited in photonic crystal heterostructure amplifiers, is predicted and the hysteresis loop and other attending phenomena are described. The bistability behavior and modulation response efficiency demonstrate the potential possibilities of the photonic crystal heterostructures with n–i–p–i layers as high-speed optical amplifiers and switches.      

Lasing efficiency of dyes incorporated into a nanoporous glass-polymer composite

We have used microsecond coherent pumping to study the lasing efficiency of active elements based on a nanoporous glass-polymer composite activated by organic dyes, as a function of the spectral composition of the pump within the main absorption band of the dye. We have shown that under the indicated excitation conditions, the lasing efficiency can exceed 40% and can be comparable with the lasing of liquid elements. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 708–716, September–October, 2008.     

Hydrogen bonds of anti-HIV active aminophenols

Analysis of IR-Fourier spectra from solutions and crystals of antiviral sulfo-containing aminophenols has shown that various types of intramolecular and intermolecular interactions can occur in molecules of these compounds. Three types of intramolecular hydrogen bonds (O–H⋅⋅⋅N, O–H⋅⋅⋅O=S=O, and N–H⋅⋅⋅O=S=O) are formed in CCl₄ solutions of the sulfo-containing aminophenols. The formation of intermolecular H-bonds involving the NH- and OH-groups and the preservation of the intramolecular O–H⋅⋅⋅O=S=O H-bond are characteristic of the anti-HIV active aminophenol crystals. Spectral attributes are determined in order to distinguish between the anti-HIV active and inactive sulfo-containing aminophenols.     

Holographic DFB laser with fan-shaped grating for a spectrofluorimeter

A method for recording fan-shaped transmitting phase holographic gratings that ensure tuning of the wavelength of emission for a DFB (distributed-feedback) dye laser is presented. Traditional optical elements are used in the scheme of grating recording. A change in the degree of grating fanning is reached here without replacement of gratings. The possibility of obtaining frequency-tuned emission by means of the fan-shaped gratings created is demonstrated experimentally. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 48–51, January–February, 2000.     

Heat treatment-induced bond layer diffusion and re-crystallization in copper carbon interface systems measured by modulated IR radiometry

Copper-carbon interface systems with additional Mo bond layers in the range of 25 nm to 200 nm have been analyzed with respect to their effective thermal depth profiles before and after heat treatment using modulated IR radiometry. Comparing the inverse calibrated modulated IR phase lags before and after heat treatment, several effects can be identified: – (1) The effusivity of the interface layer, which – due the contact resistance between the two elements copper and carbon – is rather low before heat treatment, increases considerably with heat treatment. – (2) This effect is accompanied by an increase of the thermal diffusion time of the interface layer, relying on the diffusion of Mo and Cu particles. – (3) The sputter-deposited copper films, which before heat treatment can be characterized as effective multi-layer structures, re-crystallize with heat treatment and show modulated IR phases, which are characteristic for thermally homogeneous thin films. – (4) The thermal diffusion times of the Cu films decrease considerably with heat treatment due to increased thermal diffusivities, and – (5) the thermal effusivities of the Cu films increase with heat treatment.     

Symmetry of the nonlinear collision operator matrix and new prospects in the moment method for solving the Boltzmann equation

Traditionally, the moment method has been used in kinetic theory to calculate transport coefficients. Its application to the solution of more complicated problems runs into enormous difficulties associated with calculating the matrix elements of the collision operator. The corresponding formulas for large values of the indices are either lacking or are very cumbersome. In this paper relations between matrix elements are derived from very general principles, and these can be employed as simple recurrence relations for calculating all the nonlinear and linear anisotropic matrix elements from assigned linear isotropic matrix elements. Efficient programs which implement this algorithm are developed. The possibility of calculating the distribution function out to 8–10 thermal velocities is demonstrated. The results obtained open up prospects for solving many topical problems in kinetic theory. Zh. Tekh. Fiz. 69, 6–9 (September 1999)     

Self-diffusion of lithium,hydrogen, and oxygen ions in crystalline lithium hydroxide

The self-diffusion coefficients of ions of the three chemical elements forming lithium hydroxide have been determined by the crystal-crystal and crystal-gas isotope exchange method in the temperature range 500–720 K. Crystal samples with different isotope compositions have been grown by the Bridgman method from melts. The melting temperature is 743 ± 2 K. Original methods have been developed for high-precision measurements of the isotope ratios of all three elements, i.e., lithium (⁶Li/⁷Li), hydrogen (H/D), and oxygen (¹⁶O/¹⁸O), and their changes after diffusion annealings with the use of the same sample. The self-diffusion coefficients of lithium and hydrogen ions differ but by a factor of no more than 3–5; however, their values exceed those for oxygen by several orders of magnitude. In particular, at 670 K, they are equal to 6.0 × 10⁻⁹, 3.2 × 10⁻⁹, and 2.0 × 10⁻¹² cm² s⁻¹ for hydrogen, lithium, and oxygen, respectively. In the range 680–720 K, the self-diffusion coefficients of hydrogen and lithium increase sharply with increasing temperature to approximately 10⁻⁶ cm² s⁻¹. A probable mechanism of migration of protons and lithium ions in LiOH and the role played in this process by the oxygen ions with a lower mobility have been discussed.     

Validated Spectroflurimetric Determination of Some H1 Receptor Antagonist Drugs in Pharmaceutical Preparations Through Charge Transfer Complexation

A validated simple, rapid, and selective spectrofluorimetric method was developed for the determination of some antihistaminic H₁ receptor antagonist drugs namely ebastine (EBS), cetirizine dihydrochloride (CTZ), and fexofenadine hydrochloride (FXD). The method is based on the reaction of the cited drugs with some Π acceptors namely p-chloranilic acid (CLA), tetracyanoethylene (TCNE), and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) to give highly fluorescent derivatives. The fluorescence intensity—concentration plots were rectilinear over the concentration ranges of 0.2–3.0, 0.2–2.5 and 0.15–2.0 μg/ml for EBS with CLA, DDQ, and TCNE respectively; 0.5–7.0, 0.5–6.0, and 0.2–4.0 μg/ml for CTZ with the previously mentioned reagents, and 0.2–3.5, 0.5–6.0, and 0.2–3.5 μg/ml for FXD. The factors affecting the formation of the reaction products were carefully studied and optimized. The method was applied for the determination of the studied drugs in their dosage forms. The results obtained were in good agreement with those obtained by the comparison methods. Reactions Stoichiometries of the complexes formed between the studied drugs and Π acceptors were defined by the Job’s method of the continuous variation and found in 1:1 in all cases.     

Matrix-assisted laser desorption mass spectrometry of gas-phase peptide–metal complexes

Cation attachment to a model peptide has been investigated in matrix-assisted laser desorption experiments. Angiotensin I (Asp–Arg–Val–Tyr–Ile–His–Pro–Phe–His–Leu) is chosen as a system for study, and Cu²⁺ and K⁺ salts are used as cationizing agents. Three fundamentally different types of samples are investigated: (1) a crystalline sample of Ang I, metal salt and MALDI matrix, prepared with the conventional dried droplet method; (2) a solvent-free fine powder mixture of the same three compounds, and (3) a solution of the angiotensin and the metal salt in an ionic liquid matrix (a molten organic salt that acts as a MALDI active solvent). Effective protonation and cationization of the peptide are achieved with the three methods. The transition metal systematically provides more efficient cationization than the alkali metal. At sufficiently high concentration of the salt, the attachment of up to four copper cations to the angiotensin is observed in the MALDI spectrum. In contrast, only one K⁺ cation is efficiently bound to the peptide. For a given salt concentration, the highest degree of cationization is obtained in the laser desorption from the ionic liquid matrix. This is attributed to the efficient transfer of free metal cations to the desorption plume, where the complexation takes place.     

Formation of SERS-active silver structures on the surface of mesoporous silicon

We have optimized the procedure for preparation of nanostructured silver films on the surface of mesoporous silicon (PSi) to use them as active substrates in surface-enhanced Raman scattering (SERS) spectroscopy. The greatest enhancement of the SERS signal was observed for samples obtained when the silver was deposited on PSi from an aqueous AgNO₃ solution with concentration 1⋅10^–2 M over a 10–15 minute period. The detection limit for rhodamine 6G on SERS-active substrates prepared by the optimized procedure was 1⋅10^–10 M. The enhancement factor for the SERS signal on these surfaces was estimated as ≈2⋅10⁸. We have shown that SERS-active substrates based on mesoporous silicon are promising for detection and study of complex organic compounds, in particular tetrapyrrole molecules. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 2, pp. 298–306, March–April, 2009.     

Superconducting nano-striplines as quantum detectors

The recent progress in the nanofabrication of superconducting films opens the road toward detectors with highly improved performances. This is the case for superconducting nano-striplines where the thickness and the width are pushed down to the extreme limits to realize detectors with unprecedented sensitivity and ultra fast response time. In this way quantum detectors for single photons at telecommunication wavelengths and for macromolecules such as proteins can be realized. As is often the case in applied nanotechnology, it is a challenge to make devices with the necessary macroscopic dimensions that are needed to interface present technologies, while maintaining the performance improvements. For nano-stripline detectors, both the fast temporal response and the device sensitivity is generally degraded when the area is increased. Here, we present how such detectors can be scaled up to macroscopic dimensions without losing the performance of the nano-structured active elements by using an innovative configuration. In order to realize ultrathin superconducting film the nano-layer is growth with a careful setup of the deposition technique which guarantees high quality and thickness uniformity at the nano-scale size. The active nano-strips are defined with the state-of-the-art electron beam nanolithography to achieve a highly uniform linewidth. We present working detectors based on nano-strips with thicknesses 9–40 nm and widths of 100–1000 nm which exhibit unprecedented speed and area coverage (40 × 40 μm² for single photon detectors and 1 × 1 mm² for single molecule detectors) based on niobium nitride thus enabling practical use of this nanotechnology.     

Use of diffusion wave spectroscopy in diagnostics of blood

The method of diffusion-wave spectroscopy based on the analysis of fragments of temporal autocorrelation functions or power spectra of intensity fluctuations of scattered coherent laser radiation is considered as applied to noninvasive in vitro diagnostics of blood. The results of experiments on noninvasive diagnostics of blood in vitro are interpreted within the framework of the theory of diffusion wave spectroscopy. The proposed method can be recommended for laboratory and clinical investigations of formed blood elements. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 515–519, July–August, 2000.