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  • 1
    Electronic Resource
    Electronic Resource
    Stability constant of Fe2+ chelates with soluble ligands from incubated soils (1987)
    Springer
    Biology and fertility of soils 5 (1987), S. 88-92 
    Details
    ISSN: 1432-0789
    Keywords: Ferrous iron ; Fe2+ chelates ; Stability constants ; Anearobic decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The stability constants (log K) of Fe2+ chelates were determined on the basis of the shift in peak potential during the reduction of Fe2+ by a consortium of soluble ligands from incubated soils. Log K values ranged from 2.6 to 4.5. On average a change in pH of 1 unit induced a change in log K of 0.92 units. Aeration of the anaerobic decomposition products increased log K. The log K for Fe2+ chelates was about 0.8 units larger than that for Mn2+ chelates. It is considered that the chelation of ferrous iron plays an important role in the mobility and availability of iron to plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00264352
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  • 2
    Electronic Resource
    Electronic Resource
    Strong ultraviolet photoluminescence from silicon oxide films prepared by magnetron sputtering (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 356-358 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Intense ultraviolet photoluminescence centered at 370 nm was observed from magnetron-sputtered silicon oxide films after they were annealed at about 1000 °C in N2 atmosphere. This photoluminescence is found to be associated with the formation of nanocrystal silicon particles in the specially structured SiO2, which highly resembles the oxide layer of porous silicon. The luminescence centers at the interface between the nanocrystal silicon particles and the SiO2 matrix are responsible for the strong ultraviolet luminescence. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120735
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  • 3
    Electronic Resource
    Electronic Resource
    Annealing temperature dependence of Raman scattering in Ge+-implanted SiO2 films (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 2704-2706 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have examined the Raman spectra of violet and infrared emitting Ge+-implanted SiO2 films with special emphasis upon annealing temperature (AT) dependence of Raman scattering. We found that the complete spectrum mainly consists of three bands at 220–280, 300, and 430 cm−1, corresponding to scattering of Ge-related components, Ge nanocrystallites, and localized Si–Si optical phonons in the Ge neighborhoods, respectively. The Ge crystalline band shows an obvious AT dependence. The theoretical result from the phonon confinement model can predict its linewidth change with AT, but cannot explain its constant peak frequency. Based on the experimental result from x-ray diffraction, we attributed the discrepancy mainly to the compressive stress exerted on Ge nanocrystallites, which leads to the upshift of Ge crystallite peak thereby basically compensating the downshift caused by the confinement on phonon frequency. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366089
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  • 4
    Electronic Resource
    Electronic Resource
    Enhanced ultraviolet photoluminescence from SiO2/Ge:SiO2/SiO2 sandwiched structure (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 3134-3136 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: SiO2/Ge:SiO2/SiO2 sandwiched structure was fabricated for exploring efficient light emission. After annealed in N2 (O2〈1%), this structure shows three photoluminescence (PL) bands at 293, 395, and 780 nm. The intensity of the 395 nm band is largely enhanced in comparison with that from the monolayered Ge:SiO2 film. Spectral analyses suggest that the three PL bands originate from S1→S0, T∑(T∏)→S0, and T∏′→S0 optical transitions in GeO color centers, respectively. The improvement of the GeO density resulting from the confinement on Ge diffusion is responsible for the enhanced ultraviolet PL. This structure is expected to have important applications in optoelectronics. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1325399
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  • 5
    Electronic Resource
    Electronic Resource
    The pseudo-ordered structure in light emitting porous and nanocrystalline silicon films (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 2265-2267 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structures of light emitting porous and nanocrystalline silicon films have been investigated using high resolution electron microscopy. A pseudo-ordered structure has been found from the Fourier transformation of the high resolution images after digital processing of the images. The structure description was distinguished from common amorphous and nanocrystalline silicon films. The formation mechanism of the pseudo-ordered structure is described in the letter. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118834
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  • 6
    Electronic Resource
    Electronic Resource
    Observation of folded acoustic phonons in nanocrystalline silicon/amorphous silicon multilayers (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 1855-1857 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report in this letter the observation of folded acoustic phonons in hydrogenated nanocrystalline silicon/amorphous silicon multilayers with visible emission, which are prepared in a plasma enhanced chemical vapor deposition system. In the low-frequency range of 10–100 cm−1, the obtained Raman spectra clearly show some folded doublets from longitudinal acoustic phonons. Using the elastic continuum model, we calculated their frequencies and the obtained results were in agreement with the experimental ones. In addition, some broad folded doublets and additional peaks were clearly observed in the sample with thin nancorystalline sublayers. We attributed them to the mixing of longitudinal and transverse acoustic phonons due to the layered structure. A confined acoustic mode was also proposed to be responsible for the strongly folded longitudinal acoustic phonon peak at 61 cm−1. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117456
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  • 7
    Electronic Resource
    Electronic Resource
    Phonon properties and microstructure of annealed LiTaO3:Nd (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 2401-2403 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Phonon properties and microstructure of annealed Nd-doped LiTaO3 (LT:Nd) were examined by means of Raman scattering and infrared spectra. Raman spectra show the splitting of A1(TO) mode at 204 cm−1 and the appearance of an additional shoulder peak at ∼208 cm−1, indicating that the homogeneous distribution of Nd ions leads to the structural recovery of partial oxygen octahedra centered with Li and Ta ions, but the microstructural deviation from original LT trigonal system still exists. The enhancement of E(TO) mode intensities and the reduction of A1(TO) mode intensities in the A1+E symmetry spectrum are mainly attributed to the microstructural deviation of LT:Nd and the changed photorefractive effect due to annealing. Infrared spectra in the OH stretching region suggest that the changed photorefractive effect arises from the displacements of positive ions along the optical z axis. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118884
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  • 8
    Electronic Resource
    Electronic Resource
    X-ray diffraction study of alternating nanocrystalline silicon/amorphous silicon multilayers (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 838-840 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Structural properties of alternating nanocrystalline silicon/amorphous silicon multilayers with visible light emission at room temperature were examined by means of x-ray diffraction. According to the linewidths and intensities of the diffraction peaks in the low- and high-angle ranges, we have determined the effective interface thickness, the mean crystallite sizes, and the internal strains, which are closely related to the photoluminescence in this material. In addition, the existence of the voids or holes was also observed, indicating that the improved electrical properties of this kind of hydrogenated nanocrystalline materials are due to the inhomogeneous structure of the material. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118219
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  • 9
    Electronic Resource
    Electronic Resource
    Photovoltage spectra of silicon/porous silicon heterojunction
    Amsterdam : Elsevier
    Solid State Communications 91 (1994), S. 341-343 
    Details
    ISSN: 0038-1098
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0038-1098(94)90630-0
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  • 10
    Electronic Resource
    Electronic Resource
    Voltage-controlled electroluminescence from SiO2 films containing Ge nanocrystals and its mechanism (2000)
    Springer
    Applied physics 71 (2000), S. 299-303 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 78.60.Fi; 78.66Jg; 78.66Db
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. Luminescent SiO2 films containing Ge nanocrystals are fabricated by using Ge ion implantation, and metal–oxide–semiconductor structures employing these films as the active layers show yellow electroluminescence (EL) under both forward and reverse biases. The EL spectra are strongly dependent on the applied voltage, but slightly on the mean size of Ge nanocrystals. When the forward bias increases towards 30 V, the EL spectral peak shifts from 590 nm to 485 nm. It is assumed that the EL originates from the recombination of injected electrons and holes in Ge nanocrystals near the Si/SiO2 interface, or through luminescent centers in the SiO2 matrix near the SiO2/metal interface. The mismatch of the injection amounts between holes and electrons results in the low EL efficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003390000518
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