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1
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Bioconjugation of Silver Nanowires with Photosynthetic Light-Harvesting Complexes

100%
Olejnik M., Twardowska M., Zaleszczyk W., Mackowski S.
Acta Physica Polonica A
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2012
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vol. 122
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issue 2
357-364
EN
We demonstrate a way to conjugate a light-harvesting complex, peridinin-chlorophyll-protein, with silver nanowires using biotin-streptavidin linker. In the case of conjugated structure we observe slight increase of the fluorescence intensity of the chlorophyll emission followed by the gradual decrease of the intensity due to photobleaching. For a non-conjugated mixture of peridinin-chlorophyll-protein with silver nanowires only the photobleaching takes place. The results suggest a possible way to fabricate hybrid nanostructures comprising light-harvesting complexes and metallic nanoparticles for achieving the efficient plasmon-induced enhancement of absorption of the light-harvesting complexes.
2
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The Effect of Surface Preparation on Physical Properties of Ni-ZnSe Junctions

88%
Chusnutdinow S., Makhniy V., Aleszkiewicz M., Zaleszczyk W., Slotov M.
Acta Physica Polonica A
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2014
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vol. 126
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issue 5
1076-1078
EN
We report on optical and photovoltaic properties of Ni-ZnSe junctions. We demonstrate that the preparation method of the ZnSe surface determines luminescence, optical transmission of ZnSe substrates and photovoltaic spectra of the Ni-ZnSe junctions. The observed effects are explained by formation of low-dimensional quantum structures on the ZnSe surface in result of the surface preparation procedure. This is confirmed by atomic force microscopy studies, which show the presence of grains with lateral dimensions of 30-300 nm on ZnSe surface. The smallest grains are responsible for a wide spectral band observed in photoluminescence at 3.4 eV, i.e., at much higher energies than the energy gap of bulk ZnSe, E_{g} ≈ 2.7 eV.
3
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Gold Nanoparticles with Elongated Shapes: Synthesis and Optical Properties

88%
Olejnik M., Agarwal A., Zaleszczyk W., Kotov N., Mackowski S.
Acta Physica Polonica A
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2012
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vol. 122
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issue 2
346-349
EN
We use a seed-mediated growth to fabricate gold nanorods in water solution. By changing the amount of silver salt we demonstrate the control of aspect ratio of the obtained rods. The microscopic and spectroscopic analyses provide ways to characterize the morphology and the optical properties of the gold nanorods. Nanorods synthesized using this approach feature length of the order of 50-60 nm, which translates into longitudinal plasmon resonances in the near infrared spectrum region.
4
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Anharmonic Optical Phonon Effects in ZnO Nanocrystals

76%
Khusnutdinov S., Dynowska E., Zaleszczyk W., Makhniy V., Wysmołek A., Korona K.
Acta Physica Polonica A
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2011
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vol. 119
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issue 5
678-680
EN
Zinc oxide (ZnO) is a very promising material for optoelectrical devices operating at the short-wavelength end of the visible spectral range and at the near UV. The Raman scattering studies of ZnO heterolayers formed by isothermal annealing show sharp phonon lines. In addition to the A_1(TO), E_1(TO), E_2^{H}, and E_1(LO) one-phonon lines, we observed two-phonon lines identified as: E_2^{H} - E_2^{L}, E_2^{H} + E_2^{L}, and 2LO at 332, 541, and 1160 cm^{-1}, respectively (at room temperature). The identification of the E_2^{H} - E_2^{L} peak was confirmed by its thermal dependence. Temperature dependent measurements in the range 6-300 K show that the phonon frequencies decrease with temperature. The E_2^{H} peak is at energy 54.44 meV (439.1 cm^{-1}), at 4 K and due to phonon-phonon anharmonic interaction, its energy decreases to 54.33 meV (438.2 cm^{-1}) at room temperature. The Grüneisen parameter found for this oscillation mode was γ_{E} 2H = 1.1 at about 300 K. The intensity of the E_2^{H} - E_2^{L} peak increases strongly with temperature and this dependence can be described by the Bose-Einstein statistics with activation energy of 13.8 meV (nearly equal to the energy of the E_2^{L} phonon).
5
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Magnetic Force Microscopy Study of Zn_{1-x}Co_{x}O Nanowires Grown by Rapid Thermal Evaporation

64%
Aleszkiewicz M., Fronc K., Aleszkiewicz P., Zaleszczyk W., Dziawa P., Wojciechowski T., Wojtowicz T., Karczewski G.
Acta Physica Polonica A
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2009
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vol. 116
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issue 5
865-867
EN
In this work we studied domain structure of Zn_{1-x}Co_{x}O nanowires which are single arms of tetrapode crystals. The as-grown material exhibits hysteretic behavior even at room temperature as revealed by SQUID mesurements. In order to get insight into the magnetic properties of individual tetrapodes they were dismembered into nanowires of nanometric diameters, deposited on a flat substrate and imaged by magnetic force microscopy. A magnetic interaction between the magnetic force microscopy probe and single nanowires has been detected which confirms that nanometric volume of the material possesses a magnetic moment. The magnetic force microscopy contrast is attractively independent of the tip magnetization direction which indicates that shape anisotropy of nanowires is not strong enough to prevent occurrence of tip-induced magnetic field disturbance.
6
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Reduction of the Optical Losses in CdTe/ZnTe Thin-Film Solar Cells

64%
Chusnutdinow S., Pietruszka R., Zaleszczyk W., Makhniy V., Wiater M., Kolkovsky V., Wojtowicz T., Karczewski G.
Acta Physica Polonica A
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2014
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vol. 126
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issue 5
1072-1075
EN
We report on reduction of optical losses in n-CdTe/p-ZnTe thin-film solar cells grown by molecular beam epitaxy. The investigated thin-film devices were grown from elemental sources on monocrystalline, semi-insulating, (100)-oriented GaAs substrates. The optical losses have been reduced by a texturing of the device surface and by depositing of a ZnO antireflection coating. Current-voltage and spectral characteristics of the investigated p-ZnTe/n-CdTe solar cells depend significantly on the preparation of the surface of the ZnTe window. We describe a procedure of chemical etching of the ZnTe window leading to surface texturing. A ZnO layer of proper thickness deposited by low-temperature atomic layer deposition technique on the ZnTe surface forms an effective antireflection coating that leads to the reduction of optical losses. Due to reduction of the optical losses we observe increase of the short-circuit current, J_{SC}, by almost 60% and of the energy conversion efficiency by 44%.
7
Content available remote

Physical Properties of ZnCoO Tetrapods and Nanofibers

52%
Gas K., Fronc K., Dziawa P., Knoff W., Wojciechowski T., Zaleszczyk W., Baranowska-Korczyc A., Morhange J., Paszkowicz W., Elbaum D., Karczewski G., Wojtowicz T., Szuszkiewicz W.
Acta Physica Polonica A
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2009
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vol. 116
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issue 5
868-870
EN
In this paper the physical properties of two types of Co-doped ZnO nanostructures: tetrapods and nanofibers grown by a rapid thermal evaporation process and prepared by the electrospinning technique, respectively, were investigated and analyzed. Surface morphology of the samples was examined using scanning electron microscopy. X-ray diffraction measurements showed hexagonal wurtzite crystal structure of both types of investigated nanostructures. Both X-ray diffraction and Raman scattering data confirmed high phase purity of the samples. The magnetic properties studied with the use of the SQUID magnetometer confirmed a presence of ferromagnetic order in analyzed nanostructures. The observed photoluminescence spectra exhibited two groups of lines. The first one, in the ultraviolet spectral range, is due to the optical transitions close to ZnO band gap, the second one in the red region is most probably related to the Co^{2+} d-d internal transitions. The influence of native defects on the optical properties is also shown and discussed. All results reported here lead us to the conclusion that in the mixed crystal nanostructures obtained, a fraction of the Zn^{2+} ions is substituted by Co^{2+} ions.
8
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Photoluminescence Properties of ZnO Nanowires Grown on Ni Substrate

52%
Zaleszczyk W., Fronc K., Przeździecka E., Janik E., Czapkiewicz M., Wróbel J., Paszkowicz W., Kłopotowski Ł., Karczewski G., Wojtowicz T., Presz A.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1451-1456
EN
Photoluminescence studies of zinc oxide nanowires produced by a carbo-thermal method on a nickel foil substrate are reported. Two types of as-grown samples: the first - containing only buffer film, and the second - containing both zinc oxide nanowires and buffer film grown in the same technological process, were investigated by means of the temperature-dependent photoluminescence. X-ray diffraction measurements of buffer film show that it is polycrystalline and is composed from wurtzite-type ZnO (main phase) and includes minority phases: rock salt type (Ni,Zn)O and hexagonal C₃N₄. The shape of the apparently monocrystalline nanowires is characterized by hexagonal section matching with the expectations of the hexagonal ZnO structure. The presence of LO-phonon replicas in photoluminescence spectra for the second sample is used as an argument for confirmation that ZnO nanowires are single crystalline. The method of growth of ZnO nanowires on nickel oxide opens perspectives to produce Zn_{1-x}Ni_{x}O diluted magnetic semiconductor nanowires.
9
Content available remote

Photoluminescence Properties of ZnO and ZnCdO Nanowires

52%
Zaleszczyk W., Fronc K., Aleszkiewicz M., Paszkowicz W., Wróbel J., Dłużewski P., Kret S., Klepka M., Kłopotowski Ł., Karczewski G., Wojtowicz T.
Acta Physica Polonica A
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2007
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vol. 112
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issue 2
357-362
EN
We report on the photoluminescence studies of ZnO and ZnCdO nanowires grown on SiO_2/Si substrates by low-pressure vapor phase synthesis. X-ray diffraction and transmission electron microscopy measurements show that the crystallographic structure of these ZnO and ZnCdO nanowires is of wurtzite-type with a high crystal perfection. Surface morphology of samples was determined by scanning electron microscopy and atomic force microscopy. The photoluminescence spectra of as-grown nanowires, nanowires extracted from the substrate and deposited onto Si wafer, and nanowires dispersed in ethanol by sonication were investigated at room temperature and compared to each other. The temperature dependence of the near band-gap photoluminescence emitted by the as-grown nanowires was also measured and analyzed.
10
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Morphology and Selected Properties of Core/Shell ZnTe-Based Nanowire Structures Containing ZnO

52%
Gas K., Janik E., Zaleszczyk W., Pasternak I., Dynowska E., Fronc K., Kolkovsky V., Kret S., Morhange J., Reszka A., Wiater M., Caliebe W., Karczewski G., Kowalski B., Szuszkiewicz W., Wojtowicz T.
Acta Physica Polonica A
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2011
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vol. 119
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issue 5
612-614
EN
We report on an approach to fabricate ZnTe-based core/shell radial heterostructures containing ZnO, as well as on some of their physical properties. The molecular beam epitaxy grown ZnTe nanowires constituted the core of the investigated structures and the ZnO shells were obtained by thermal oxidation of ZnTe NWs. The influence of the parameters characterizing the oxidation process on selected properties of core/shell NWs were examined. Scanning electron microscopy revealed changes of the NWs morphology for various conditions of the oxidation process. X-ray diffraction, high resolution transmission electron microscopy, and Raman scattering measurements were applied to reveal the presence of ZnTe single crystal core and polycrystalline ZnO-shell of investigated structure.
11
Content available remote

Growth and Properties of ZnMnTe Nanowires

46%
Zaleszczyk W., Janik E., Presz A., Szuszkiewicz W., Morhange J., Dłużewski P., Kret S., Kirmse H., Neumann W., Dynowska E., Domagała J., Caliebe W., Aleszkiewicz M., Pacuski W., Golnik A., Kossacki P., Baczewski L., Petroutchik A., Karczewski G., Wojtowicz T.
Acta Physica Polonica A
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2007
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vol. 112
|
issue 2
351-356
EN
Catalytically enhanced growth of ZnMnTe diluted magnetic semiconductor nanowires by molecular beam epitaxy is reported. The growth is based on the vapor-liquid-solid mechanism and was performed on (001) and (011)-oriented GaAs substrates from elemental sources. X-ray diffractometry, scanning and transmission electron microscopy, atomic force microscopy, photoluminescence spectroscopy, and Raman scattering were performed to determine the structure of nanowires, their chemical composition, and morphology. These studies revealed that the obtained ZnMnTe nanowires possess zinc-blende structure, have an average diameter of about 30 nm, typical length between 1 and 2μm and that Mn^{2+} ions were incorporated into substitutional sites of the ZnTe crystal lattice.
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