| 1. |
- Midander, Klara, et al.
(författare)
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Characterisation of nano- and micron-sized airborne and collected subway particles, a multi-analytical approach
- 2012
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 427, s. 390-400
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Tidskriftsartikel (refereegranskat)abstract
- Continuous daily measurements of airborne particles were conducted during specific periods at an underground platform within the subway system of the city center of Stockholm, Sweden. Main emphasis was placed on number concentration, particle size distribution, soot content (analyzed as elemental and black carbon) and surface area concentration. Conventional measurements of mass concentrations were conducted in parallel as well as analysis of particle morphology, bulk- and surface composition. In addition, the presence of volatile and semi volatile organic compounds within freshly collected particle fractions of PM 10 and PM 2.5 were investigated and grouped according to functional groups. Similar periodic measurements were conducted at street level for comparison.The investigation clearly demonstrates a large dominance in number concentration of airborne nano-sized particles compared to coarse particles in the subway. Out of a mean particle number concentration of 12000 particles/cm 3 (7500 to 20000 particles/cm 3), only 190 particles/cm 3 were larger than 250nm. Soot particles from diesel exhaust, and metal-containing particles, primarily iron, were observed in the subway aerosol. Unique measurements on freshly collected subway particle size fractions of PM 10 and PM 2.5 identified several volatile and semi-volatile organic compounds, the presence of carcinogenic aromatic compounds and traces of flame retardants.This interdisciplinary and multi-analytical investigation aims to provide an improved understanding of reported adverse health effects induced by subway aerosols.
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| 2. |
- Belova, Liubov M., et al.
(författare)
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Rapid preparation of electron beam induced deposition Co magnetic force microscopy tips with 10 nm spatial resolution
- 2012
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 83:9, s. 093711-
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic force microscope Co spike tips with lateral magnetic resolution of 10 nm have been prepared. The Co spikes are grown by electron beam induced deposition of Co from Co-2(CO)(8) gas precursor. The high resolution Co spikes are fabricated at the spot of a tightly focused electron beam on the tip of commercial atomic force microscope cantilevers. Qualitative investigations indicate that a spike grown on a planar base of Co improves the signal to noise.
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| 3. |
- Biswas, Anis, et al.
(författare)
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The effect of oxygen partial pressure during deposition in the magnetic properties of ZnO thin film
- 2011
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Ingår i: Mater Res Soc Symp Proc. - : Springer Science and Business Media LLC. - 9781605112695 ; , s. 117-122
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Konferensbidrag (refereegranskat)abstract
- We have studied the magnetic properties of 100 nm thick ZnO thin films prepared by magnetron sputtering in different oxygen partial pressures (ratio of oxygen pressure to total pressure in deposition chamber, P Oxy). Only the films fabricated at P Oxy below ∼ 0.5 show room temperature ferromagnetism. The saturation magnetization at room temperature is initially found to increase as P Oxy increases and reaches maximum value of ∼ 5 emu/gm at P Oxy ∼ 0.3 and then starts to decrease and becomes diamagnetic for P Oxy > 0.5. From small angle XRD study of structural properties of the films, we find that the lattice stress developed in the film along c-axis also exhibits a similar behavior with the variation of P Oxy. Thus, both the room temperature ferromagnetism and lattice stress appear to originate from the intrinsic defects present in the sample.
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| 4. |
- Chia, Han-Jong, et al.
(författare)
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Nanoscale Spin Wave Localization Using Ferromagnetic Resonance Force Microscopy
- 2012
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 108:8, s. 087206-
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Tidskriftsartikel (refereegranskat)abstract
- We use the dipolar fields from a magnetic cantilever tip to generate localized spin wave precession modes in an in-plane magnetized, thin ferromagnetic film. Multiple resonances from a series of localized modes are detected by ferromagnetic resonance force microscopy and reproduced by micromagnetic models that also reveal highly anisotropic mode profiles. Modeled scans of line defects using the lowest-frequency mode provide resolution predictions of (94.5 +/- 1.5) nm in the field direction, and (390 +/- 2) nm perpendicular to the field.
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| 5. |
- Chia, Han-Jong, et al.
(författare)
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Spectroscopic defect imaging in magnetic nanostructure arrays
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 101:4, s. 042408-
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a method for imaging defective structures in an array of magnetic nanodevices using ferromagnetic resonance force microscopy with contrast between normal and defective devices provided through differences in resonance condition. In a demonstration of this technique, two dimensional scans of an array resolve not only intentional differences in resonant field between 200 nm circular dots and an intentional oval "defect," but also smaller differences between the nominally identical circular dots in the array.
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| 6. |
- Chia, Han-Jong, et al.
(författare)
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Two-dimensional spectroscopic imaging of individual ferromagnetic nanostripes
- 2012
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 86:18, s. 184406-
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Tidskriftsartikel (refereegranskat)abstract
- We use ferromagnetic-resonance force microscopy to spectroscopically image the edge modes in individual 700 nm and 400 nm wide Permalloy stripes with a spatial resolution on the order of 200 nm. The imaging clearly identifies some resonances as edge modes in stripes in a case where mode identification by comparison with micromagnetic modeling is not clear. Combined spectroscopic and spatial scans reveal clear differences in the edge mode resonances at opposite edges of the stripes as well as inhomogeneity along the length of the stripe.
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| 7. |
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| 8. |
- Fischer, Andreas, et al.
(författare)
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Synthesis, structure, and magnetic properties of some layered compounds based on long-chain sulfonium cations and complex cobalt and copper anions
- 2013
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Ingår i: Zeitschrift für Anorganische und Allgemeines Chemie. - : Wiley. - 0044-2313 .- 1521-3749. ; 639:14, s. 2613-2617
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Tidskriftsartikel (refereegranskat)abstract
- Two new materials of the composition ({CH3(CH2) 15(CH3)2S}+)2[CoBr 4]2- (1) and ({CH3(CH2) 15(CH3)2S}+)2[CuBr 4]2- (2 and 3), of which the latter exists in two polymorphs, were synthesized. The materials display the synthetically targeted structures, comprising of layers of complex metal ions and layers of long-chain sulfonium cations. The crystal structures of the materials were determined. The interlayer distances are around 24 Å, with metal-metal distances about 8 Å. The magnetic properties of 1 were investigated, and the material is paramagnetic. ({CH3(CH2)15(CH3) 2S}+)2[CuBr4]2 is polymorphic. Both polymorphs crystallize with triclinic symmetry.
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| 9. |
- Guo, Feng, et al.
(författare)
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Parametric pumping of precession modes in ferromagnetic nanodisks
- 2014
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 89:10, s. 104422-
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Tidskriftsartikel (refereegranskat)abstract
- We report on the parametric excitation of magnetic precession modes in nanodisks using a parallel pumping configuration. The excitations are detected using a ferromagnetic resonance force microscopy method, and the parallel-pumped spectra reveal nonlinear characteristics including instability thresholds and multiple, narrow, sawtooth-shaped resonances. These characteristics are in accord with analytical theory and micromagnetic modeling results. Modeled mode profiles of the excitations show that higher-order standing spin-wave modes with both even and odd symmetries are excited under parallel pumping.
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| 10. |
- Guo, Feng, et al.
(författare)
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Spectroscopy and Imaging of Edge Modes in Permalloy Nanodisks
- 2013
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 110:1, s. 017601-
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Tidskriftsartikel (refereegranskat)abstract
- We report ferromagnetic resonance force microscopy of confined spin-wave modes with improved, 100 nm resolution. The ferromagnetic resonance spectra in Permalloy disks (diameters ranging from 100 to 750 nm) distinguish multiple edge modes, and the images reveal distinct precession patterns. The fundamental edge mode also provides a new, localized probe of the magnetic properties of the film edge; rotation of the applied field reveals large edge property variations in nominally circular disks. As a function of disk diameter, the number of observed edge modes agrees with modeling.
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