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Jan Misiewicz

Bio: Jan Misiewicz is an academic researcher from Wrocław University of Technology. The author has contributed to research in topics: Photoluminescence & Quantum well. The author has an hindex of 32, co-authored 585 publications receiving 6195 citations.


Papers
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Journal ArticleDOI
TL;DR: In this article, the influence of the nanocrystal matrix on the optical properties of lanthanide dopants is investigated with europium ions used as local crystal field probes, and the analysis is performed on small NaYF4 and NaGdF4 nanocrystals obtained by the thermolysis of the corresponding metal trifluoroacetates.
Abstract: The influence of the nanocrystal matrix on the optical properties of lanthanide dopants is investigated with europium ions used as local crystal field probes. The analysis is performed on small NaYF4 and NaGdF4 nanocrystals obtained by the thermolysis of the corresponding metal trifluoroacetates. An important role in the synthesis is played by trioctylphosphine oxide which induces the crystallization of nanocrystals with small diameters (∼5 to 6 nm). In such small particles, the energy transfer from gadolinium to europium ions is studied with photoluminescence, photoluminescence excitation and time-resolved experiments. We demonstrate that excited gadolinium ions efficiently transfer their energy to europium, and their photoluminescence spectra depend on the nanocrystal size. This is contrary to the direct excitation of Eu3+ ions, which produces size-dependent emission corresponding to the surface to volume ratio of europium sites. Finally, we propose that Gd3+ ions transfer their energy mainly to the Eu3+ in the core of the nanocrystals. These observations provide a base for the optically controlled emission from only the core of the nanocrystals.

66 citations

Journal ArticleDOI
TL;DR: Carrier spin coherence in a p-doped GaAs/(Al,Ga)As quantum well with a diluted hole gas with resonant optical excitation shows two types of oscillations: Electron spin beats decaying with the charged exciton radiative lifetime of 50 ps, and long-lived hole spin beats with dephasing times up to 650 ps, underlining the importance of hole localization.
Abstract: Carrier spin coherence in a $p$-doped $\mathrm{GaAs}/(\mathrm{Al},\mathrm{Ga})\mathrm{As}$ quantum well with a diluted hole gas is studied by picosecond pump-probe Kerr rotation. For resonant optical excitation of the positively charged exciton the spin precession shows two types of oscillations: Electron spin beats decaying with the charged exciton radiative lifetime of 50 ps, and long-lived hole spin beats with dephasing times up to 650 ps, which decrease with increasing temperature, underlining the importance of hole localization. The mechanism of hole spin coherence generation is discussed.

59 citations

Journal ArticleDOI
TL;DR: In this paper, the growth by molecular beam epitaxy of GaBixAs1−x epilayers on (311)B GaAs substrates was reported, and the incorporation of Bi into the GaBiAs alloy, as determined by HRXRD, is sizably larger in the ( 311)B epilayer than in (001) epil layers, giving rise to reduced band-gap energies as obtained by optical transmission spectroscopy.
Abstract: We report the growth by molecular beam epitaxy of GaBixAs1−x epilayers on (311)B GaAs substrates. We use high-resolution x-ray diffraction (HRXRD), transmission electron microscopy, and Z-contrast imaging to characterize the structural properties of the as-grown material. We find that the incorporation of Bi into the GaBiAs alloy, as determined by HRXRD, is sizably larger in the (311)B epilayers than in (001) epilayers, giving rise to reduced band-gap energies as obtained by optical transmission spectroscopy.

59 citations

Journal ArticleDOI
TL;DR: Truly alloyed PbS(x)Se(1-x) (x = 0-1) nanocrystals (∼5 nm in size) have been prepared, and their resulting optical properties are red-shifted systematically as the sulfur content of the materials increases.
Abstract: Truly alloyed PbS(x)Se(1-x) (x = 0-1) nanocrystals (similar to 5 nm in size) have been prepared, and their resulting optical properties are red-shifted systematically as the sulfur content of the materials increases. Their optical properties are discussed using a modified Vegard's approach and the bowing parameter for these nanoalloys is reported for the first time. The alloyed structure of the nanocrystals is supported by the energy-filtered transmission electron microscope images of the samples, which show a homogeneous distribution of sulfur and selenium within the nanocrystals. X-ray photoelectron spectroscopy studies on ligand-exchanged nanocrystals confirmed the expected stoichiometry and various oxidized species.

58 citations

Journal ArticleDOI
TL;DR: In this paper, a semiempirical tight-binding electronic-energy-band structures of the following semiconductors are presented: (i) Cd, Cc, Zn, and Zn.
Abstract: Semiempirical tight-binding electronic-energy-band structures of the following ${\mathrm{II}}_{3}$${\mathrm{V}}_{2}$ semiconductors are presented: ${\mathrm{Cd}}_{3}$${\mathrm{P}}_{2}$, ${\mathrm{Zn}}_{3}$${\mathrm{P}}_{2}$, ${\mathrm{Cd}}_{3}$${\mathrm{As}}_{2}$, and ${\mathrm{Zn}}_{3}$${\mathrm{As}}_{2}$. The zinc-blende approximation of the real crystal structure was used. The calculations were carried out within the nearest- and second-nearest-neighbor approximation and the single s and p atomic-orbital basis set. The tight-binding parameters were obtained empirically by fitting calculated density of valence states and reflectivity spectra to the empirical spectrum. The presented parametrization of the band structures provides an accurate representation of the valence bands and an adequate description of the lowest and most important conduction bands of ${\mathrm{II}}_{3}$${\mathrm{V}}_{2}$ semiconductors.

52 citations


Cited by
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28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1(PfPMP1)与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员,通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

18,940 citations

Journal ArticleDOI
01 Apr 1988-Nature
TL;DR: In this paper, a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) is presented.
Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

9,929 citations

Journal ArticleDOI

2,877 citations

Book ChapterDOI
27 Jan 2010

878 citations

Journal ArticleDOI
TL;DR: In this paper, the state of the art in this rapidly growing field is discussed and new classes of materials that open up new possibilities for extended functionality and greater optoelectronic integration are described.

809 citations