Now showing items 58-77 of 1046

    • Femtosecond pulse generation with a diode-pumped Yb3+:YVO4 laser 

      Kisel, V. E.; Troshin, A. E.; Shcherbitsky, V. G.; Kuleshov, N. V.; Matrosov, V. N.; Matrosova, T. A.; Kupchenko, M. I.; Brunner, F.; Paschotta, R.; Morier-Genoud, F.; Keller, U. (Optical Society of America, 2005)
      A diode-pumped Yb:YVO4 laser has been passively mode locked for the first time, to our knowledge. 120 fs pulses with an average output power of 300 mW and a peak power as high as 14.5 kW are obtained by use of a semiconductor saturable-absorber mirror for passive mode locking. The optical spectrum has a 10 nm bandwidth (full width at half-maximum) and is centered at 1021 nm.
      2012-01-23
    • Femtosecond pulse operation of a Tm,Ho-codoped crystalline laser near 2 μm 

      Lagatsky, A. A.; Fusari, F.; Calvez, S.; Kurilchik, S. V.; Kisel, V. E.; Kuleshov, N. V.; Dawson, M. D.; Brown, C. T. A.; Sibbett, W. (Optical Society of America, 2010)
      We demonstrate, for the first time to our knowledge, femtosecond-regime mode locking of a Tm,Ho-codoped crystalline laser operating in the 2 μm spectral region. Transform-limited 570 fs pulses were generated at 2055 nm by a Tm,Ho:KY(WO4)2 laser that produced an average output power of 130 mW at a pulse repetition frequency of 118 MHz. Mode locking was achieved using an ion-implanted ...
      2012-01-23
    • Fluorescence line narrowing study of cyclopentaneporphyrin chemical dimers at 4.2 K 

      Starukhin, A.; Zenkevich, E. I.; Shulga, A.; Chernook, A. (1996)
      The monomers of Zn-cyclopentanporphyrins (ZnOEP-cycle and ZnOEP-cycle=CH2) and their chemical dimers covalently linked via isocycles (Zn-cyclodimers) have been studied by the method of fluorescence line narrowing (FLN) in tetrahydrofurane-toluene (3:1) glassy matrixes at 4.2 K. Well-resolved fluorescence spectra upon laser excitation into the S₀→S₁ absorption band have been ...
      2017-05-18
    • Formation and optical properties of self-organized pentameric porphyrin arrays 

      Chernook, A. V.; Rempel, U.; Borczyskowski, C. von; Zenkevich, E. I.; Shulga, A. (1996)
      Principles of formation, electronic absorption and fluorescence spectra are reported for self-organized pentameric arrays of tetrapyrrolic macrocycles. In these arrays two molecules of Zn-porphyrin dimers, Zn(II)l,4-bis[5-(10,15,20-tri-p-hexylphenylporphyrinyl)]-benzene ((ZnHTPP)₂) are bound via one molecule of a tetrapyridyl-substituted free base of porphyrin or tetrahydroporphyrin. ...
      2017-05-25
    • Formation of Cone-Shaped Inclusions and Line Defects on the Cz-Si Wafer Surface by the Helium Implantation and DC Nitrogen Plasma Treatment 

      Frantskevich, N. V.; Mazanik, A. V.; Frantskevich, A. V.; Koltunowicz, T.; Zukowski, P. (2011)
      The general goal of this work is to investigate the defects formed on the surface of the Cz-Si wafers subjected to helium implantation, vacuum annealing and nitrogen plasma treatment. The performed scanning electron microscopy study has shown that in the general case two types of surface defects can be formed: cone-shaped inclusions with the base diameter of 0.2-2 mu m and the ...
      2018-03-10
    • Formation Principles and Ligand Dynamics for Nanoassemblies of CdSe Quantum Dots and Functionalized Dye Molecules 

      Blaudeck, T.; Zenkevich, E.; Abdel-Mottaleb, M.; Szwaykowska, K.; Kowerko, D.; Cichos, F.; Borczyskowski, C. von (2012)
      Functional dye molecules, such as porphyrins, attached to CdSe quantum dots (QDs) through anchoring meso-pyridyl substituents, form quasi-stable nanoassemblies. This fact results in photoluminescence (PL) quenching of the QDs both due to Förster resonance energy transfer (FRET) and the formation of non-radiative surface states under conditions of quantum confinement (non-FRET). ...
      2017-05-27
    • Graphene Q-Switched Compact Yb: YAG Laser 

      Serres, J. M.; Jambunathan, V.; Mateos, X.; Loiko, P.; Lucianetti, A.; Mocek, T.; Yumashev, K.; Petrov, V.; Griebner, U.; Aguilo, M.; Diaz, F. (2015)
      We describe a compact Yb: YAG laser Q-switched by a graphene-based saturable absorber and pumped by a laser diode at 932 or 969 nm. The compact laser generates a maximum average output power value of 185 mW at 1032 nm with a slope efficiency value of 12%. The shortest duration of the Q-switched pulse achieved is 228 ns at a repetition frequency of 285 kHz. The maximum pulse energy ...
      2018-03-06
    • Highly efficient continuous-wave diode-pumped Er, Yb:GdAl3(BO3)4 laser 

      Kisel, V. E.; Gorbachenya, K. N.; Yasukevich, A. S.; Maltsev, V. V.; Leonyuk, N. I.; Kuleshov, N. V. (Optical Society of America, 2013)
      We report the highly efficient continuous-wave diode-pumped laser operation of Er, Yb:GdAl3 BO3 4 crystal. Absorption and stimulated emission spectra, emission lifetimes, and efficiencies of energy transfer from Yb3 to Er3 ions were determined. A maximal output power of 780 mWwas obtained at 1531 nm at absorbed pump power of 4 W with slope efficiency of 26%.
      2016-01-05
    • Ho:KLuW microchip laser intracavity pumped by a diode-pumped Tm:KLuW laser 

      Serres, J. M.; Loiko, P. A.; Mateos, X.; Yumashev, K. V.; Kuleshov, N. V.; Petrov, V.; Griebner, U.; Aguilo, M.; Diaz, F. (Springer, 2015)
      A compact intracavity-pumped microchip Ho laser is realized using stacked Tm:KLuW/Ho:KLuW crystals pumped by a laser diode at 805 nm; both crystals are cut for light propagation along the Ng optical indicatrix axis and emit with polarization along the Nm axis. Maximum CW output power of 285 mW is achieved at a wavelength of 2080 nm for 5.6 W absorbed pump power in the Tm:KLuW ...
      2018-09-14
    • Identification and assignment of porphyrin-CdSe Hetero-nanoassemblies 

      Zenkevich, E. I.; Blaudeck, T.; Shulga, A. M.; Cichos, F.; Borczyskowski, C. von (2007)
      Hetero-nanoassemblies in toluene solution are formed via anchoring pyridyl substituted free base porphyrin molecules on the colloidal core-shell semiconductor nanocrystals CdSe/ZnS. The formation can be identified via quenching of semiconductor photoluminescence and followed via spectral changes of porphyrin spectral properties such as fluorescence, fluorescence decay and absorption. ...
      2017-05-27
    • In-band pumped room-temperature Er:KY(WO4)2 laser emitting around 1:6 mm 

      Gorbachenya, K. N.; Kisel, V. E.; Yasukevich, A. S.; Pavlyuk, A. A.; Kuleshov, N. V. (Maik Nauka-Interperiodica Publishing, 2013)
      We present efficient continuous-wave operation of an Er:KY(WO 4)2 crystal under in-band pumping by a compact diode-pumped Er, Yb:GdAl3(BO3)4 laser. Maximum slope efficiency of 27% and output power of 35 mW at 1609.5 nm were obtained with beam propagation factor M2 < 1:2. Absorption and stimulated emission cross-section spectra, as well as the radiative lifetime of the 4I13=2 ...
      2016-05-12
    • Influence of Brownian Diffusion on Levitation of Bodies in Magnetic Fluid 

      Bashtovoi, V. G.; Reks, A. G.; Klimovich, C.; Motsar, A.; Ryapolov, P. A.; Storozhenko, A.; Shabanova, I. (Sumy State University, 2013)
      The present work deals with experimental investigation of the levitation of magnetic and non-magnetic bodies in a magnetic fluid when essentially influenced by Brownian diffusion of magnetic particles in it. It is established that the point of levitation of bodies in a magnetic fluid varies with time.
      2016-03-29
    • Influence of Shell Parameters on Optical Properties of Spherical Metallic Core-Oxide Shell Nanoparticles 

      Pustovalov, V. K.; Astafyeva, L. G. (2015)
      Different metal homogeneous nanoparticles have been extensively studied in recent years due to their wide range of potential applications. It is very interesting to investigate core-shell nanoparticles with oxide shell from core metal. The formation of oxide shell on metallic nanoparticles can be achieved by different chemical and physical methods including also natural oxidation ...
      2017-11-04
    • Influence of Single Dye Molecules on Temperature and Time Dependent Optical Properties of CdSe/ZnS Quantum Dots: Ensemble and Single Nanoassembly Detection 

      Zenkevich, E. I.; Stupak, A. P.; Kowerko, D.; Borczyskowski, C. von (2012)
      Optical spectroscopy on ensembles and single CdSe/ZnS semiconductor quantum dots (QDs) demonstrates a competition of trap and near band edge photoluminescence (PL). This competition can be markedly influenced by a few surface attached pyridyl functionalized dye molecules (porphyrins or perylene diimides) forming nanoassemblies with well defined geometries. Temperature variation ...
      2017-05-27
    • Influence of the meridional flow and thermomagnetic convection on characteristics of magnetic fluid seal 

      Krakov, M. S.; Nikiforov, I. V. (Maik Nauka-Interperiodica Publishing, 2011)
      For the low-speed magnetic fluid seals, the influence of the meridional flow, induced by the shaft rotation, on the distribution of magnetic particles concentration, is studied. Influence of the thermomagnetic convection on the structure of this flow and on the temperature distribution in high-speed magnetic fluid seals is investigated also. The problems were examined by numerical ...
      2016-03-29
    • Insensitivity of the Stationary Distribution of State Probabilities in an Open Network with Non-Active Customers 

      Kruk, Yu. S.; Dudovskaya, Yu. E. (2015)
      We study the stationary operation of an open queueing network with non-active customers and informational signals. The amount of work to service a claim is a random value with an arbitrary distribution. The stationary distribution of network state probabilities has a multiplicative form and is insensitive with respect to the functional form of the distribution of the work needed ...
      2017-11-21
    • Interaction of multiporphyrin systems with molecular oxygen in liquid solutions: Extra-ligation and screening effects 

      Sagun, E. I.; Zenkevich, E. I.; Knyukshto, V. N.; Shulga, A. M.; Starukhin, D. A.; Borczyskowski, C. von (2002)
      Steady-state and time-resolved studies indicate that for a sequence of porphyrin or chlorin chemical dimers Zn-cyclodimer → (ZnOEP)₂Ph → (ZnOEP)₂ → (ZnHTPP)₂ → (ZnOEChl)₂ with relative lowering of excited S₁- and T₁-states, the extra-ligation by pyridine (PYR) does not influence essentially on fluorescence parameters but leads to an increase of T₁-states non-radiative decay (the ...
      2017-05-26
    • Internal scheme of the body assessment in an experiment with environmental uncertainty 

      Lukashevich, U. A.; Vasuk, V. E.; Tarasevich, M. I.; Mankevich, S. M.; Paramonova, N. A. (2017)
      The aim of the work was to analyze the influence of various environmental factors forming environmental uncertainty on the nature of the transformation of the "internal scheme of the body". Materials and methods. For the study, a group of healthy volunteers (n = 90) was selected. The results in this paper are median, 75 and 25 percentiles (Me [UQ / LQ]). The study was conducted ...
      2022-08-29
    • International higher education cooperation under conditions of fuzzy terminology: intellectual mobility vector 

      Mannanov, U. V.; Gancherenok, I. I. (2030 Uzbekistan Research Online, 2020)
      Terminology analysis of higher education internationalization process concerning joint educational programs is fulfilled. Fuzziness of used terminology is demonstrated. Joint higher education establishments development in the framework of fractal model is suggested as a strategic direction of higher education internationalization, enhancement of its quality and a concept of ...
      2020-07-17
    • Investigations of Chl α aggregates cross-linked by dioxane in 3-methylpentane 

      Oksanen, J. A. I.; Zenkevich, E. I.; Knyukshto, V. N.; Pakalnis, S.; Hynninen, P. H.; Korrpi-Tommola, J. E. I. (1997)
      In this work, dioxane-bound aggregates of chlorophyll a are prepared in 3-methylpentane. The properties of the aggregates are studied by using steady-state and time-resolved spectroscopies. The Qy-region absorption spectrum of the chlorophyll α-dioxane aggregate shows four clearly resolvable narrow bands with comparable intensities. The band maxima are located at 683, 689, 698 ...
      2017-05-25