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| 10. |
- Dovner, PO, et al.
(author)
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The occurrence of lower hybrid cavities in the upper ionosphere
- 1997
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In: GEOPHYSICAL RESEARCH LETTERS. - : AMER GEOPHYSICAL UNION. - 0094-8276. ; 24:5, s. 619-622
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Journal article (other academic/artistic)abstract
- Lower hybrid cavities (LHC), i. e., small-scale density depletions coinciding with enhanced lower hybrid waves, are frequent in the upper ionosphere. It is found that they exist in all regions the Freja satellite has scanned, as long as lower hybrid waves
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| 11. |
- Gustafsson, G, et al.
(author)
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The electric field and wave experiment for the Cluster mission
- 1997
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In: Space Science Reviews. - 0038-6308 .- 1572-9672. ; 79, s. 137-156
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Journal article (peer-reviewed)abstract
- The electric-field and wave experiment (EFW) on Cluster is designed to measure the electric-field and density fluctuations with sampling rates up to 36 000 samples s(-1). Langmuir probe sweeps can also be made to determine the electron density and temperature. The instrument has several important capabilities. These include (1) measurements of quasi-static electric fields of amplitudes lip to 700 mV m(-1) with high amplitude and time resolution, (2) measurements over short periods of time of up to five simualtaneous waveforms (two electric signals and three magnetic signals from the seach coil magnetometer sensors) of a bandwidth of 4 kHz with high time resolution, (3) measurements of density fluctuations in four points with high time resolution. Among the more interesting scientific objectives of the experiment are studies of nonlinear wave phenomena that result in acceleration of plasma as well as large- and small-scale interferometric measurements. By using four spacecraft for large-scale differential measurements and several Langmuir probes on one spacecraft for small-scale interferometry, it will be possible to study motion and shape of plasma structures on a wide range of spatial and temporal scales. This paper describes the primary scientific objectives of the EFW experiment and the technical capabilities of the instrument.
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| 12. |
- Gustafsson, G, et al.
(author)
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The electric field and wave experiment for the Cluster mission
- 1997
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In: SPACE SCIENCE REVIEWS. - : KLUWER ACADEMIC PUBL. - 0038-6308. ; 79:1-2, s. 137-156
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Journal article (peer-reviewed)abstract
- The electric-field and wave experiment (EFW) on Cluster is designed to measure the electric-field and density fluctuations with sampling rates up to 36 000 samples s(-1). Langmuir probe sweeps can also be made to determine the electron density and tempera
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| 15. |
- Karlsson, M, et al.
(author)
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Equilibrium and structural studies of silicon(IV) and aluminium(III) in aqueous solution. 33. The Al(methylmalonate)(2)(H2O)(2)(-) complex crystallised as a double salt with Al(H2O)(6)(3+) and Cl-
- 1998
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In: Acta Chemica Scandinavica. - 0904-213X .- 1902-3103. ; 52:8, s. 995-999
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Journal article (peer-reviewed)abstract
- The crystal structure of hexaaquaaluminium(III) trans-diaquabis(2-methylpropanedionate)aluminate(III) dichloride tetrahydrate, [Al(H2O)(6)(3+)] [Al(C4H4O4)(2)(H2O)(2-)][Cl-](2 .)4H(2)O, was determined by single-crystal X-ray diffraction. The compound crystallises in the triclinic space group , with a = 6.956(1), b = 8.413(2), c = 10.737(2) Angstrom, alpha = 89.78(2), beta = 106.90(2), gamma = 95.25(2)degrees and Z = 1. The refinement of 148 parameters on 2563 reflections [I > 2.0 sigma(I)] gave a final R-value of 0.076 (R-w = 0.052, S = 1.082). The double salt was crystallised from aqueous solution and contains two different octahedral aluminium complexes, an Al(H2O)(6)(3+) complex and an AlL2(H2O)(2)(-) complex with two methylmalonate ions equatorially coordinated and with two molecules of water at the apices. The structure is built up from layers of the Al complexes alternated with layers of chloride ions and water molecules parallel to the (010) plane.
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| 16. |
- Karlsson, M, et al.
(author)
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Equilibrium and structural studies of silicon(IV) and aluminium(III) in aqueous solution. 34. A crystal structure determination of the Al(methylmalonate)(2)(CH3OH)(2)(-) complex with Na+ as counter-ion
- 1998
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In: Acta Chemica Scandinavica. - 0904-213X .- 1902-3103. ; 52:9, s. 1116-1121
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Journal article (peer-reviewed)abstract
- The crystal structure of sodium bis(trans)-2-methylpropanedionatedimethanolaluminate(III), [Na+][Al(C4H4O4)(2)(CH3OH)(2)(-)], has been determined by single crystal X-ray diffraction. The compound crystallises in the trigonal space group R (3) over bar, with a = 12.046(2), c= 28.705(6) Angstrom and Z= 9. The refinement of 103 parameters on 946 reflections [1>2.0 sigma(I)] gave a final R-value of 0.064 (R-w= 0.066, S= 1.000). The structure consists of octahedral Al(C4H4O4)(2)(CH3OH)(2)(-) complexes and sodium ions. In these complexes, methylmalonate coordinates to Ak(3+) bidentately in the equatorial plane of the octahedron, while methanol coordinates at the apices. As such, it represents a rare single-crystal example of direct aluminium( III)-methanol coordination. The complexes, arranged in layers, are connected to each other by octahedrally coordinated sodium ions, in special position 6c, and hydrogen bonds. The layers, with the methyl group of methylmalonate pointing out from the layers, are stacked perpendicular to the [001] direction and are held together by other octahedrally coordinated sodium ions, in special position 3b.
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| 17. |
- Lyxell, D G, et al.
(author)
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Multicomponent polyanions .48. The crystal structure of trihydrogen dodecamolybdophosphate-benzene(1/3)
- 1996
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In: Acta Chemica Scandinavica. - 0904-213X .- 1902-3103. ; 50:11, s. 985-990
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Journal article (peer-reviewed)abstract
- A novel organic solvated heteropoly compound, H3Mo12PO40. 3(C6H6), crystallised in the monoclinic form, P2(1)/n (No. 14), with a = 12.189(2), b = 13.981(2), c = 12.978(1) Angstrom and beta = 98.59(1)degrees. The refinement of 340 parameters with 3705 reflections [I > 3.0 sigma(I)] gave a final R-value of 0.061 (R(w) = 0.067). The polyanion, having a so-called alpha-Keggin structure, is disordered around an inversion centre. One of three benzene molecules is sandwiched between polyanions, and the other two are accommodated in a cavity surrounded by polyanions. The links between polyanions and benzene rings are mainly due to hydrogen bonds. The phosphate and benzene in the compound were formed by hydrolysis of phenylphosphonate. (C) Acta Chemica Scandinavica 1996.
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| 18. |
- Lyxell, D G, et al.
(author)
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Multicomponent polyanions. 53. Structure of tetrakis(trimethylammonium) tetra-mu-oxo-bis(triaquahexadecaoxo(trioxophenylphosphato)hexamolybdate) dihydrate, [NH(CH3)(3)](4)[{(C6H5P)Mo6O21(H2O)(3)}(2)].2H(2)O
- 1998
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In: Acta Crystallographica Section B. - 0108-7681 .- 1600-5740. ; 54, s. 424-430
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Journal article (peer-reviewed)abstract
- The title compound crystallized in the monoclinic space group P2(1)/n (No. 14) [a = 11.211 (5), b = 12.862 (3), c = 23.05 (1) Angstrom, beta = 94.37 (3)degrees, V = 3314 (2) Angstrom(3), Z = 2]. The polyanion can be regarded as a dimer of a phenylphosphonatohexamolybdate, (C6H5P)Mo6O23(H2O)(3), Linked by four O atoms. In this monomeric unit the six molybdenum octahedra are grouped into two parts consisting of four and two edge-sharing octahedra, respectively. These two parts are connected by two corner-sharing O atoms to form a bent Mo-6 ring. The phenylphosphonate group coordinates to the Mo-6 ring from the narrow side as a tripodal Ligand. The {(C6H5P)Mo6O21 (H2O)(3)}(2) units form layers parallel to (001) and the structure is stabilized by hydrogen bonds between water and neighboring anions. The monomeric unit has been shown to be a key structure in the process of deducing the aqueous solution structures of the (C6H5P)Mo-6(2-) and (C6H5P)Mo-7(4-) species found in a previous equilibrium study of the H+-MoO42-(C6H5P)O-3(2-) system.
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| 19. |
- Lyxell, D G, et al.
(author)
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Multicomponent polyanions. 54. Crystal structure of tetracaesium monohydrogen phosphato(phosphito)pentamolybdate dihydrate, Cs-4[H(HP)PMo5O22]center dot 2H(2)O
- 1998
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In: Acta Chemica Scandinavica. - 0904-213X .- 1902-3103. ; 52:4, s. 425-430
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Journal article (peer-reviewed)abstract
- The crystal structure of tetracaesium monohydrogen phosphato (phosphito)pentamolybdate dihydrate was determined by single-crystal X-ray diffraction. The compound crystallises in the triclinic space group P (1) over bar, a=10.284(2), b= 10.791(2) and c=13.047(3) Angstrom, alpha=109.34(2), beta=99.92(2) and gamma=102.85(2)degrees, V=1283.4(5) Angstrom(3) and Z=2. The final R-values are R=0.066, wR=0.039 and S=1.3667. The H(HP)PMo5O224- anion has common features with the Strandberg X2M5-type heteropolyanion. The five MoO6 octahedra form a five-membered ring by one corner-sharing and four edge-sharing connections, and the tripodal phosphate and phosphite ligands protrude from each side of this ring in opposite directions. This is the first example of the structure of the heteropolyoxometalate having both P-III and P-V as heteroatoms.
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