| 1. |
- Aad, G, et al.
(författare)
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- 2015
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swepub:Mat__t
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| 2. |
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| 3. |
- Aaron, F. D., et al.
(författare)
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Combined measurement and QCD analysis of the inclusive e(+/-)p scattering cross sections at HERA
- 2010
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :1
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Tidskriftsartikel (refereegranskat)abstract
- A combination is presented of the inclusive deep inelastic cross sections measured by the H1 and ZEUS Collaborations in neutral and charged current unpolarised e(+/-)p scattering at HERA during the period 1994-2000. The data span six orders of magnitude in negative four-momentum-transfer squared, Q(2), and in Bjorken x. The combination method used takes the correlations of systematic uncertainties into account, resulting in an improved accuracy. The combined data are the sole input in a NLO QCD analysis which determines a new set of parton distributions, HERAPDF1.0, with small experimental uncertainties. This set includes an estimate of the model and parametrisation uncertainties of the fit result.
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| 4. |
- Aaron, F. D., et al.
(författare)
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Events with an isolated lepton and missing transverse momentum and measurement of W production at HERA
- 2010
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2010:3, s. 1-19
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Tidskriftsartikel (refereegranskat)abstract
- A search for events containing an isolated electron or muon and missing trans verse momentum produced in e(+/-)p collisions is performed with the H1 and ZEUS detectors at HERA. The data were taken in the period 1994-2007 and correspond to an integrated luminosity of 0.98 fb(-1). The observed event yields are in good overall agreement with the Standard Model prediction, which is dominated by single W production. In the e(+)p data, at large hadronic transverse momentum P-T(X) > 25GeV, a total of 23 events are observed compared to a prediction of 14.0 +/- 1.9. The total single W boson production cross section is measured as 1.06 +/- 0.16 (stat.) +/- 0.07 (sys.) pb, in agreement with an Standard Model (SM) expectation of 1.26 +/- 0.19 pb.
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| 5. |
- Aaron, F. D., et al.
(författare)
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Multi-leptons with high transverse momentum at HERA
- 2009
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; :10
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Tidskriftsartikel (refereegranskat)abstract
- Events with at least two high transverse momentum leptons (electrons or muons) are studied using the H1 and ZEUS detectors at HERA with an integrated luminosity of 0.94 fb(-1). The observed numbers of events are in general agreement with the Standard Model predictions. Seven di- and tri-lepton events are observed in e(+)p collision data with a scalar sum of the lepton transverse momenta above 100 GeV while 1.94 +/- 0.17 events are expected. Such events are not observed in e(-)p collisions for which 1.19 +/- 0.12 are predicted. Total visible and differential di-electron and di-muon photoproduction cross sections are extracted in a restricted phase space dominated by photon-photon collisions.
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| 6. |
- Alcorn, J, et al.
(författare)
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Basic instrumentation for Hall A at Jefferson Lab
- 2004
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 522:3, s. 294-346
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Tidskriftsartikel (refereegranskat)abstract
- The instrumentation in Hall A at the Thomas Jefferson National Accelerator Facility was designed to study electro-and photo-induced reactions at very high luminosity and good momentum and angular resolution for at least one of the reaction products. The central components of Hall A are two identical high resolution spectrometers, which allow the vertical drift chambers in the focal plane to provide a momentum resolution of better than 2 x 10(-4). A variety of Cherenkov counters, scintillators and lead-glass calorimeters provide excellent particle identification. The facility has been operated successfully at a luminosity well in excess of 10(38) CM-2 s(-1). The research program is aimed at a variety of subjects, including nucleon structure functions, nucleon form factors and properties of the nuclear medium. (C) 2003 Elsevier B.V. All rights reserved.
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| 7. |
- Faatz, B., et al.
(författare)
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Simultaneous operation of two soft x-ray free-electron lasers driven by one linear accelerator
- 2016
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Extreme-ultraviolet to x-ray free-electron lasers (FELs) in operation for scientific applications are up to now single-user facilities. While most FELs generate around 100 photon pulses per second, FLASH at DESY can deliver almost two orders of magnitude more pulses in this time span due to its superconducting accelerator technology. This makes the facility a prime candidate to realize the next step in FELs-dividing the electron pulse trains into several FEL lines and delivering photon pulses to several users at the same time. Hence, FLASH has been extended with a second undulator line and self-amplified spontaneous emission (SASE) is demonstrated in both FELs simultaneously. FLASH can now deliver MHz pulse trains to two user experiments in parallel with individually selected photon beam characteristics. First results of the capabilities of this extension are shown with emphasis on independent variation of wavelength, repetition rate, and photon pulse length.
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| 8. |
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| 9. |
- Toropov, A. A., et al.
(författare)
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InAs/Zn(Mn)Te/Cd(Mn)Se pseudomorphic quantum well structures for spintronic applications
- 2004
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Ingår i: 11th International Conference on II-VI Compounds,2003. - : WileyVCH. ; , s. 704-
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Konferensbidrag (refereegranskat)abstract
- Zn(Mn)Te/Cd(Mn)Se quantum well heterostructures have been grown pseudomorphically on InAs(001) substrates using original InAs surface preparation techniques. The structures demonstrated bright PL in the 1-1.3 eV range and the effect of giant Zeeman splitting in the external magnetic field.
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| 10. |
- Evropeytsev, E. A., et al.
(författare)
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Structural properties and vertical transport in ZnSe/CdSe superlattices grown on an In0.3Ga0.7As metamorphic buffer layer
- 2016
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Ingår i: PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 13 NO 7-9. - : WILEY-V C H VERLAG GMBH. ; , s. 503-506
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Konferensbidrag (refereegranskat)abstract
- We report on the growth by molecular-beam epitaxy of short-period ZnSe/ CdSe superlattices (SLs) on an In0.3Ga0.7As metamorphic buffer layer. Such SLs are considered as a promising material for a wide band-gap photoactive p-n junction in a hybrid monolithic Ge/InxGa1-xAs/In-y(Al,Ga)(1-y)As/II-VI solar cell. Lattice-matching of the SLs to the In0.3Ga0.7As layer is confirmed by X-ray diffractometry. Vertical transport of photoexcited carriers is investigated by means of both steady state and time-resolved photoluminescence techniques in heterostructures containing the ZnSe/CdSe SL with an enlarged quantum well (EQW). Characteristic times of the carrier transport across the SL towards EQW are evaluated in the temperature range 120-300 K. (C) 2016 WILEY-VCH Verlag GmbH amp; Co.
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| 11. |
- Maksimchuk, Pavel O. O., et al.
(författare)
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·OH-Free Catalytic Decomposition of H2O2 by GdVO4:Eu3+ Nanoparticles
- 2023
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Ingår i: The Journal of Physical Chemistry C. - 1932-7447 .- 1932-7455. ; 127:31, s. 15206-15214
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Tidskriftsartikel (refereegranskat)abstract
- H2O2 is known to be one of the initiators provoking biomolecules (lipids and proteins) oxidation and cell mutation and death. In this context, molecules, which can react with H2O2 without generating free radicals such as hydroxyl radicals (·OH), are of special interest as effective preventive antioxidants. In the present study, we report on GdVO4:Eu3+ nanoparticles (NPs) as prospective preventive nanozymes. Synthesized GdVO4:Eu3+ NPs were characterized by TEM, HR-TEM, XRD, SAXS, and XPS methods. It has been revealed that in water solutions GdVO4:Eu3+ NPs are in the form of individual crystalline spheroids with ? = 12.1 ± 1.23 nm and d = 5.76 ± 0.68 nm. Using the optical spectroscopy technique, the possibility for Fenton- and CAT-like reactions in water solutions containing GdVO4:Eu3+ NPs has been analyzed. The protective effect of GdVO4:Eu3+ NPs from H2O2-induced oxidative stress has been estimated using rat hepatocytes and analyzing changes in cells’ mitochondrial potential. It was concluded that the main mechanism of H2O2 decomposition both in aqueous solutions and biological milieu is rather associated with CAT-like reactions that ensure the V4+/V5+ and V3+/V4+ redox cycling.
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| 12. |
- Toropov, A. A., et al.
(författare)
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Exciton magnetic polarons in a type II ZnMnSe/ZnSSe superlattice
- 2004
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Ingår i: Physica status solidi (c)Special Issue: 11th International Conference on II–VI Compounds (II–VI 2003)Volume 1, Issue 4. - physica status solidi (c), Vol. 1, Issue 4 : WileyVCH. ; , s. 847-850
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Konferensbidrag (refereegranskat)abstract
- We present a time-resolved experimental study of excitonic magnetic polaron (EMP) dynamics in type II quantum wells ZnMnSe/ZnSSe. Two photoluminescence peaks were observed, which reflects coexistence of localized excitons and EMPs in the same sample. This was possible due to the competition of two localization mechanisms - magnetic localization of heavy holes in the ZnMnSe layers and non-magnetic localization of electrons in the ZnSSe layers.
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| 13. |
- Buyanova, Irina, 1960-, et al.
(författare)
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On the spin injection in ZnMnSe/ZnCdSe heterostructures
- 2002
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Konferensbidrag (refereegranskat)abstract
- We present results from a detailed study of spin injection in thin II-VI wide band gap semiconductor heterostructures by magnetooptical spectroscopy. It is shown that efficient spin alignment can be achieved in a diluted magnetic semiconductor barrier (a layer of ZnMnSe or ZnMnSe/CdSe superlattice) as thin as 10 nm. Rather efficient spin injection from such a thin spin aligner to a non-magnetic quantum well is demonstrated, even when the tunneling energy barrier is as thick as 10 nm. The effect of spin relaxation process on spin injection is also closely examined.
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| 14. |
- Buyanova, Irina, 1960-, et al.
(författare)
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Tunable laser spectroscopy of spin injection in ZnMnSe/ZnCdSe quantum structures
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81:12, s. 2196-
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Tidskriftsartikel (refereegranskat)abstract
- Magneto-optical spectroscopy in combination with tunable laser excitation is employed to study exciton spin alignment and injection in ZnMnSe/ZnCdSe quantum structures. This approach enables us to selectively create preferred spin orientation and to separately monitor subsequent spin injection from individual spin states, thus shedding light on a possible source of spin loss. It is shown that the limited spin polarization in a nonmagnetic quantum well due to spin injection from a ZnMnSe-based diluted magnetic semiconductor (DMS) is not caused by a limited degree of spin alignment in the DMS, which is in fact complete, but rather occurs during subsequent processes.
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| 15. |
- Ivanov, S.V., et al.
(författare)
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MBE growth and properties of bulk BeCdSe alloys and digital (BeSe : CdSe)/ZnSe quantum wells
- 2000
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Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 214, s. 109-114
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Tidskriftsartikel (refereegranskat)abstract
- We report for the first time on MBE growth, structural and optical properties of single layers, quantum well structures and short-period superlattices based on BexCd1-xSe ternary alloys on GaAs. Both the conventional MBE growth mode and the sub-monolayer digital alloying technique (SDA) have been employed for the fabrication of the structures. Compositional boundaries of an instability region 0.03 < x < 0.38, calculated in a regular solution approximation for the completely coherent system, agree well with available experimental data. A suppression of the phase separation in BeCdSe by elastic stress in the layer, accompanied by a strong reduction of the Cd incorporation coefficient has been found. Ultrathin 2.8 ML BeCdSe SDA QWs with x approx. 0.15 demonstrate about an order of magnitude increase in the PL intensity with respect to the pure CdSe one, probably resulting from an enhanced carrier localization efficiency. Eg as a function of the Be content reveals a strong bowing in optical data, which allows one to consider BeCdSe alloys with compositions nearly lattice-matched to GaAs as potential materials for the active region of blue-green lasers.
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| 16. |
- Terentev, Ya. V., et al.
(författare)
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Semimagnetic ZnMnSe/CdSe Fractional Monolayer Superlattice as an Injector of Spin-Polarized Carriers
- 2002
-
Ingår i: Physica status solidi. B, Basic research. - 0370-1972 .- 1521-3951. ; 229:2, s. 765-768
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Tidskriftsartikel (refereegranskat)abstract
- We report on effective injection of spin-oriented carriers from a semimagnetic semiconductor structure to a non-magnetic ZnCdSe/ZnSe quantum well (QW). A short-period ZnMnSe/CdSe fractional monolayer superlattice was used as a spin injector. The carriers are photo-generated in the semimagnetic region, spin-polarized via the effect of giant Zeeman splitting and then injected into the non-magnetic QW. The spin injection efficiency was estimated by circular polarization measurements of recombination emission from the QW. The maximal detected degree of the spin polarization is about 25%.
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| 17. |
- Valakh, M.Ya., et al.
(författare)
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Optical investigation of CdSe/ZnSe quantum nanostructures
- 2002
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Ingår i: Semiconductor Science and Technology. - : IOP Publishing. - 0268-1242 .- 1361-6641. ; 17:2, s. 173-177
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Tidskriftsartikel (refereegranskat)abstract
- We have used resonant and non-resonant Raman scattering as well as photoluminescence and cathodoluminescence experiments to study the structure and composition properties of CdxZn1-xSe formed by migration enhanced epitaxy of CdSe layers on ZnSe buffers. The spectral change of the photoluminescence maximum correlates with the increase of the Cd content, depending on the nominal CdSe thickness in the 1.5-3.0 ML range. The inhomogeneous broadening of the photoluminescence band is caused by the composition difference between the two-dimensional mixed CdxZn1-xSe layer and the inserted islands with larger Cd concentration. This is confirmed by phonon frequency changes in resonant Raman scattering for samples with different nominal CdSe thicknesses as well as in Stokes and anti-Stokes frequency changes observed in the 1.5 ML sample. Attention is paid to the role of defects on Raman scattering and photoluminescence for the 3.15 ML sample.
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| 18. |
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| 19. |
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| 20. |
- Toropov, A.A., et al.
(författare)
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Dynamics of excitons near the mobility edge in CdSe/ZnSe superlattices
- 2000
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Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 214, s. 806-809
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics properties of hot excitons near the effective excitonic mobility edge are investigated in a CdSe/ZnSe superlattice structure where thermalized luminescence of localized excitons is strongly suppressed due to tunneling towards the attached deeper ZnCdSe quantum well. Time-resolved selective-excitation luminescence measurements reveal a rather complicated relaxation behavior involving fast (20-30 ps) acoustical-phonon-assisted selective occupation of states located close to the mobility edge.
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| 21. |
- Toropov, A.A., et al.
(författare)
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III-V/II-VI heterovalent double quantum wells
- 2006
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Ingår i: Physica status solidi. B, Basic research. - : Wiley. - 0370-1972 .- 1521-3951. ; 243:4, s. 819-826
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Tidskriftsartikel (refereegranskat)abstract
- We report on design, fabrication by molecular beam epitaxy, and photoluminescence (PL) studies of III-V/II-VI heterovalent structures containing a GaAs/AlGaAs/ZnSe/ZnCdMnSe double quantum well (QW). The studies of temperature-dependent and time-resolved PL have provided an insight into the nature of the exciton localization potential induced by the heterovalent interface. It is found that under the resonant conditions the observed emission mostly originates from the recombination of excitons confined in type II quantum-dot-like structures, where the holes are localised within the GaAs QW due to the well width fluctuations and the electrons are localized in the plane of the ZnCdMnSe QW due to the fluctuations of the conduction band offset at the heterovalent interface, induced by random variation of the interface microscopic structure. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA,.
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| 22. |
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| 23. |
- Toropov, A.A., et al.
(författare)
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Magneto-photoluminescence studies of diluted magnetic semiconductor type-II quantum wells ZnMnSe/ZnSSe
- 2003
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Ingår i: Proceedings of the International Conference on Superlattices, Nano-structures and Nano-devices ICSNN 2002 o-structures and Nano-devices ICSNN 2002. ; , s. 352-354
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Konferensbidrag (refereegranskat)abstract
- Magneto-photoluminescence (PL) has been studied in type II Zn1-xMnxSe/ZnSySe1-y multiple quantum wells (QWs) with the Mn content x between 0.03 and 0.15. Two PL lines are observed in the samples with x equal to 0.05 and 0.15. The lines are attributed to the excitons of two different types, coexisting in the QWs. At least one of them is associated with the formation of an exciton magnetic polaron. © 2002 Elsevier Science B.V. All rights reserved.
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| 24. |
- Toropov, A. A., et al.
(författare)
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ZnMnSe/ZnSSe Type-II semimagnetic superlattices : Growth and magnetoluminescence properties
- 2002
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Ingår i: Semiconductors (Woodbury, N.Y.). - : Pleiades Publishing Ltd. - 1063-7826 .- 1090-6479. ; 36:11, s. 1288-1293
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Tidskriftsartikel (refereegranskat)abstract
- A ZnSSe/ZnMnSe type-II semimagnetic superlattice was pseudomorphically grown via molecular beam epitaxy on a GaAs substrate. The superlattice-layer thicknesses and compositions were chosen so that compressive strains in the ZnMnSe layer compensated tensile strains in the ZnSSe layer. The photoluminescence spectra in an external magnetic field demonstrate the effect of giant Zeeman splitting of an exciton. Simulation of the luminescence-line shift in a magnetic field allowed us to determine more accurately the band offsets at the ZnSSe/ZnMnSe interface.
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| 25. |
- Buyanova, Irina, 1960-, et al.
(författare)
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Control of spin functionality in ZnMnSe-based structures : Spin switching versus spin alignment
- 2003
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 82:11, s. 1700-
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Tidskriftsartikel (refereegranskat)abstract
- The ability of attaining desired spin functionality by adjusting structural design is demonstrated in diluted magnetic semiconductor (DMS) quantum structures based on II-VI semiconductors. The following spin enabling functions are achieved by tuning the ratio between the rates of exciton spin relaxation within the DMS and exciton escape from it to an adjacent nonmagnetic spin detector. Spin switching is realized when using a thin layer of Zn0.95Mn0.05Se as a spin manipulator and is attributed to a fast exciton escape from the DMS preceding the spin relaxation. Spin alignment is accomplished in tunneling structures where the presence of an energy barrier inserted between a spin manipulator (a DMS-based superlattice) and a spin detector ensures a slow escape rate from the DMS layer.
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| 26. |
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| 27. |
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| 28. |
- Buyanova, Irina, 1960-, et al.
(författare)
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Exciton Spin Manipulation in ZnMnSe-Based Structures
- 2003
-
Konferensbidrag (refereegranskat)abstract
- Strong effect of structural design on spin functionality is observed in quantum structures based on II-VI semiconductors. Spin switching is realized when using a thin layer of Zn0.95Mn0.05Se diluted magnetic semiconductor (DMS) as a spin manipulator. This is evident from the polarization of photoluminescence related to a spin detector (an adjacent nonmagnetic quantum well (QW)) measured under the resonant excitation of the spin-up and spin-down states of the DMS, which is identical in value but opposite in sign. The achieved spin switching is suggested to reflect fast carrier diffusion from the DMS due to the absence of an energy barrier between the upper spin state of the DMS layer and the QW. On the other hand, the spin alignment is accomplished in the tunneling structures where the presence of the energy barrier inserted between a spin manipulator (i.e., a ZnMnSe/CdSe DMS superlattice) and a spin detector ensures a slow escape rate from the DMS layer.
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| 29. |
- Buyanova, Irina, 1960-, et al.
(författare)
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Resonant suppression of exciton spin relaxation in Zn0.96Mn0.04Se/CdSe superlattices
- 2003
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 93:10, s. 7352-
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Tidskriftsartikel (refereegranskat)abstract
- Spin relaxation processes in strained Zn0.96Mn0.04Se/CdSe superlattices are studied in detail by using hot photoluminescence combined with tunable excitation spectroscopy. A drastic enhancement in occupation of the upper-lying |+1/2,-3/2> state of the heavy-hole excitons is observed when excitation photon energy is resonantly tuned near an integer number of the LO phonon energy above the |+1/2,-3/2> state. Assuming the Boltzmann distribution between the excitonic states, the spin temperature of the excitons is deduced to be as high as 85 K, well above the lattice temperature of 2 K. The observed behavior provides experimental evidence for a surprisingly strong suppression of spin relaxation from the upper spin-split excitonic branch for small values of wave vector.
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| 30. |
- Buyanova, Irina, 1960-, et al.
(författare)
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Transient Spectroscopy of Optical Spin Injection in ZnMnSe/ZnCdSe Quantum Structures
- 2005
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Ingår i: Journal of Superconductivity. - Journal of Superconductivity and Novel Magnetism, vol. 18 : Springer. - 0896-1107 .- 1572-9605.
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Konferensbidrag (refereegranskat)abstract
- We show, by time-resolved magneto-photoluminescence (PL) spectroscopy in combination with selective laser excitation, that optical polarization of the ZnCdSe spin detector induced by spin injection from the ZnMnSe spin injector persists over a much longer time scale than the lifetime of the ZnMnSe excitons. This finding provides compelling experimental evidence that the dominant mechanism for the observed spin injection in the ZnMnSe/ZnCdSe structures should not be due to injection of the excitonic spins of the diluted magnetic semiconductor (DMS). It is rather due to e.g. a delayed spin injection arising from tunneling of individual carriers or/and trapped spins in ZnMnSe.
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| 31. |
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| 32. |
- Chen, Weimin, 1959-, et al.
(författare)
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Efficient spin depolarization in ZnCdSe spin detector : an important factor limiting optical spin injection efficiency in ZnMnSe/CdZnSe spin light-emitting structures
- 2004
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 85, s. 5260-
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Tidskriftsartikel (refereegranskat)abstract
- Spin depolarization of a ZnCdSe quantum-well spin detector (SD) in ZnMnSe/ZnCdSe light-emitting quantum structures is investigated by cw and time-resolved optical orientation spectroscopy. It is shown that spin depolarization is governed by three distinct spin relaxation processes with the corresponding polarization decay times of 850, 30, and <10 ps. The dominant and the fastest process is attributed to spin relaxation accompanying energy relaxation of hot excitons (and hot carriers) within the SD, providing evidence that it can be an important source of spin loss, leading to the observed limited efficiency of optical spin injection in the structures.
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| 33. |
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| 34. |
- Kyutt, R N, et al.
(författare)
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X-ray diffraction determination of the interface structure of CdSe/BeTe superlattices
- 2003
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Ingår i: Journal of Physics D. - : Iop Publishing Ltd. - 0022-3727 .- 1361-6463. ; 36:10A, s. A166-A171
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Tidskriftsartikel (refereegranskat)abstract
- Structural study of CdSe/BeTe superlattices (SLs) grown by molecular beam epitaxy on GaAs substrate was performed by using double and triple crystal x-ray diffractometry. The period of the studied structures was about 5 nm, while the thickness of thin CdSe insertions varied from 0.4 to 1.5 monolayer. It is shown that new Be-Se bonds arise at the BeTe-CdSe interfaces in addition to the Be-Se bonds expected at the CdSe-BeTe interfaces. From the analysis of the diffraction curves of 002-reflection the complex composition of interfaces and thin insertions has been determined and contribution of all types of bonds in each SL period calculated. The diffraction curves of 004-reflection were used for the specification of the fine structure of the interfaces.
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| 35. |
- Toropov, A.A., et al.
(författare)
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Coexistence of type-I and type-II band lineups in Cd(Te,Se)/ZnSe quantum-dot structures
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:12
-
Tidskriftsartikel (refereegranskat)abstract
- The authors report on transmission electron microscopy, cathodoluminescence, and time resolved photoluminescence studies of thin Cd(Te,Se) layers in a ZnSe matrix, grown by molecular beam epitaxy. All observations confirm strain-induced self-assembly of quantum dots (QD's), induced primarily by the 14% lattice mismatch between CdTe and ZnSe. The emission spectrum of the structure is the superposition of a relatively narrow luminescence line originating from CdSe-enriched type-I QD's and a broad band attributed to the emission of an ultrathin ZnTeSe/ZnSe layer with type-II band lineup, formed in between the QD's. © 2006 American Institute of Physics.
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| 36. |
- Toropov, A.A., et al.
(författare)
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Density-dependent dynamics of exciton magnetic polarons in ZnMnSe/ZnSSe type-II quantum wells
- 2006
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : APS. - 1098-0121 .- 1550-235X. ; 73:24, s. 245335-
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Tidskriftsartikel (refereegranskat)abstract
- We report on time-resolved photoluminescence studies of exciton dynamics in a ZnMnSe/ZnSSe type-II quantum well. Strong separation of the electrons, confined to the nonmagnetic semiconductor ZnSSe, and holes, confined to the diluted magnetic semiconductor ZnMnSe, results in an exciton lifetime exceeding 3 ns. Two excitonic emission lines are observed in this structure at low temperatures. The lower-energy line was associated with the formation of an exciton magnetic polaron (EMP), whereas the higher-energy line was attributed to the emission of nonmagnetically localized excitons. The intensity of the EMP line was found to saturate at a relatively low density of photoexcited carriers well below the exciton Mott density. This behavior evidences a limited density of sites where the hole localization radius is small enough to ensure the fast formation of EMP's with a noticeable binding energy. © 2006 The American Physical Society.
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| 37. |
- Toropov, A.A., et al.
(författare)
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Excitons as a probe of interface morphology in Cd(Zn)Se/ZnSe heterostructures
- 2000
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 166:1, s. 278-283
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Tidskriftsartikel (refereegranskat)abstract
- We present studies of the excitonic spectrum in superlattices (SLs) of CdSe insertions in a ZnSe matrix aimed at elucidating the CdSe/ZnSe interface morphology. The experimental photoluminescence excitation spectra are compared with the results of variational exciton calculations performed within the effective mass approximation. The shape of the average vertical (along the SL growth axis) distribution of CdSe within each insertion, used in the calculations, was obtained from a theoretical simulation of X-ray diffraction (XRD) rocking curves measured in the same samples. The results indicate that the thinnest layers are graded composition ZnCdSe quantum wells (QWs), generally homogeneous in the layer planes, whereas flat islands enriched by Cd appear at the CdSe nominal thickness larger than 0.5-0.6 monolayer (ML).
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| 38. |
- Toropov, A. A., et al.
(författare)
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Magnetooptical studies of CdSe/(Zn,Mn)Se semimagnetic nanostructures
- 2000
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Ingår i: 8th International Symposium Nanostructures: Physics Technology,2000. - : Ft. Belvoir Defense Technical Information Center. ; , s. 440-443
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Konferensbidrag (refereegranskat)abstract
- In conclusion the performed magneto-PL measurements exhibit fonrmation of 0D excitons in CdSe/(Zn,Mn)Se nanostructures. The excitonic states forming the inhomogeneously broadened emission band differ both in their energy (due to fluctuations in the sizes and compositions among the localization sites) and in magnetic properties (most probably, due to the effect of Mn ions clustering in the nearby regions). The structure potential for spin-related optoelectronic applications is demonstrated, owing to almost complete circular polarization of the emitted light within the wide spectral range (about 1OO meV) at moderate magnetic fields.
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| 39. |
- Buyanova, Irina A., et al.
(författare)
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Effect of momentum relaxation on exciton spin dynamics in diluted magnetic semiconductor ZnMnSe CdSe superlattices
- 2005
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 71:16
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Tidskriftsartikel (refereegranskat)abstract
- cw hot photoluminescence (PL) complemented by transient PL measurements is employed to evaluate momentum and spin relaxation of heavy hole (HH) excitons in ZnMnSe CdSe superlattices. The rate of acoustic-phonon assisted momentum relaxation is concluded to be comparable to the total rate of exciton decay processes, about (2-3) × 1010 s-1, independent of applied magnetic fields. In magnetic fields when the Zeeman splitting ? of the exciton states is below the energy of the longitudinal optical (LO) phonon (?LO), a surprisingly strong suppression of spin relaxation rate from the bottom of the upper spin band is observed, which becomes comparable to that of momentum scattering via acoustic phonons. On the other hand, dramatic acceleration of the spin relaxation process by more than one order of magnitude is found for the excitons with a high momentum K. The findings are interpreted as being due to electron and hole spin flip processes via exchange interaction with isolated Mn2+ ions. Experimental evidence for the efficient interaction between the hot excitons and Mn impurities is also provided by the observation of spin flip transitions within Mn2+ - Mn2+ pairs that accompany the momentum relaxation of the hot HH excitons. In higher magnetic fields ?= ?LO, abrupt shortening of the spin flip time is observed. It indicates involvement of a new and more efficient spin relaxation process and is attributed to direct LO-assisted exciton spin relaxation with a subpicosecond spin relaxation time. © 2005 The American Physical Society.
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| 40. |
- Thiele, I., et al.
(författare)
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A community-driven global reconstruction of human metabolism
- 2013
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Ingår i: Nature Biotechnology. - : Springer Science and Business Media LLC. - 1087-0156 .- 1546-1696. ; 31:5, s. 419-
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Tidskriftsartikel (refereegranskat)abstract
- Multiple models of human metabolism have been reconstructed, but each represents only a subset of our knowledge. Here we describe Recon 2, a community-driven, consensus 'metabolic reconstruction', which is the most comprehensive representation of human metabolism that is applicable to computational modeling. Compared with its predecessors, the reconstruction has improved topological and functional features, including similar to 2x more reactions and similar to 1.7x more unique metabolites. Using Recon 2 we predicted changes in metabolite biomarkers for 49 inborn errors of metabolism with 77% accuracy when compared to experimental data. Mapping metabolomic data and drug information onto Recon 2 demonstrates its potential for integrating and analyzing diverse data types. Using protein expression data, we automatically generated a compendium of 65 cell type-specific models, providing a basis for manual curation or investigation of cell-specific metabolic properties. Recon 2 will facilitate many future biomedical studies and is freely available at http://humanmetabolism.org/.
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| 41. |
- Toropov, A. A., et al.
(författare)
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Magneto-photoluminescence studies of Cd(Mn)Se/Zn(Mn)Se diluted magnetic nanostructures
- 2001
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Ingår i: Physica. E, Low-Dimensional systems and nanostructures. - 1386-9477 .- 1873-1759. ; 10:1-3, s. 362-367
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Tidskriftsartikel (refereegranskat)abstract
- We report on cw and time-resolved photoluminescence (PL) studies of Cd(Mn)Se/Zn(Mn)Se diluted magnetic semiconductor nanostructures grown by molecular beam epitaxy. Excitonic PL intensity, decay time and Zeeman splitting have been studied systematically as a function of Cd(Mn)Se nominal thickness, Mn concentration and sample design. Wave function mapping has been performed, evidencing the formation of semi-magnetic quantum disk islands in the samples with thick enough Cd(Mn)Se insertions. ⌐ 2001 Elsevier Science B.V.
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| 42. |
- Bekou, V, et al.
(författare)
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Detection of laminin 5-specific auto-antibodies in mucous membrane and bullous pemphigoid sera by ELISA
- 2005
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Ingår i: Journal of Investigative Dermatology. - 1523-1747. ; 124:4, s. 732-740
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Tidskriftsartikel (refereegranskat)abstract
- Mucous membrane pemphigoid (MMP) is an autoimmune bullous disease that primarily affects mucous membranes leading to a scarring phenotype. MMP patients produce auto-antibodies (auto-ab) that preferentially recognize two components of the dermoepidermal basement membrane zone (BMZ): bullous pemphigoid (BP)180 and laminin 5 (LN5). Since detection of disease-specific auto-ab may be critical for diagnosis of MMP, we developed an ELISA with affinity-purified native human LN5. A total of 24 MMP, 72 BP, and 51 control sera were analyzed for LN5-specific auto-ab: 18/24 (75.0%) MMP and 29/72 (40.3%) BP sera were LN5 reactive. Sensitivity and specificity of the LN5 ELISA for MMP were 75% and 84.3%, respectively, and 40.3% and 88.2% for BP, respectively. The LN5 ELISA was more sensitive than a dot blot assay with native LN5, which detected LN5-reactive IgG in 14/24 (58.3%) MMP and 16/72 (22.2%) BP sera. In MMP, but not BP, levels of LN5-reactive IgG correlated with disease severity. Furthermore, IgG reactivity to LN5 of the MMP and BP sera was not significantly associated with IgG reactivity against other autoantigens of the BMZ, such as BP180 or BP230. Thus, the established LN5 ELISA holds great promise as a novel diagnostic and prognostic parameter for MMP.
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| 43. |
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| 44. |
- Lebedev, A.A., et al.
(författare)
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Studying 3C-SiC epilayers grown on the (0001)C face of 6H-SiC substrates
- 2007
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Ingår i: Technical physics letters. - 1063-7850 .- 1090-6533. ; 33:6, s. 524-526
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial 3C-SiC films grown on the (0001)C face of 6H-SiC substrates by sublimation epitaxy in vacuum have been studied. The results of x-ray diffraction measurements show evidence of a rather high structural perfection of silicon carbide epilayers. The Raman spectroscopy data confirm that the 3C-SiC layer grows immediately on the 6H-SiC substrate without any transition layers. It is concluded that the structures under consideration are well suited for the investigation of a two-dimensional electron gas at the 3C-SiC/6C-SiC heterojunction. © Nauka/Interperiodica 2007.
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| 45. |
- Mikhailov, T. N., et al.
(författare)
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Recombination dynamics in heterostructures with two planar arrays of II-VI quantum dots
- 2016
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Ingår i: 3RD INTERNATIONAL SCHOOL AND CONFERENCE ON OPTOELECTRONICS, PHOTONICS, ENGINEERING AND NANOSTRUCTURES (SAINT PETERSBURG OPEN 2016). - : IOP PUBLISHING LTD.
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Konferensbidrag (refereegranskat)abstract
- We present time-resolved photoluminescence studies of epitaxial heterostructures with two arrays of Cd(Zn)Se/ZnSe quantum dots (QDs), which are formed by the successive insertion of CdSe fractional monolayers of different nominal thicknesses into a ZnSe matrix. Our data are suggestive of the appearance of effective channels of the energy transfer from the insertion comprising the array with smaller QDs, emitting at higher energy, towards the array with larger QDs, emitting at lower energy. The effect of dark excitons on characteristic times of radiative recombination is discussed.
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| 46. |
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| 47. |
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| 48. |
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