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  • 1
    Electronic Resource
    Electronic Resource
    Raman scattering in hexagonal GaN epitaxial layer grown on MgAl2O4 substrate (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 2051-2054 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The room temperature Raman spectra of the hexagonal GaN epilayer grown on [111]- oriented MgAl2O4 substrate were measured in various backscattering and right angle scattering geometries. All of the symmetry—allowed optical phonon modes were observed except the E2 (low frequency) mode. The quasitransverse and quasilongitudinal modes were also observed in the x(zx)z and x(yy)z configurations, which are the mixed modes of pure transverse and longitudinal modes with A1 and E1 symmetry, respectively. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371007
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  • 2
    Electronic Resource
    Electronic Resource
    Photoluminescence and Raman scattering of silicon nanocrystals prepared by silicon ion implantion into SiO2 films (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 1439-1442 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence (PL) and Raman spectra of silicon nanocrystals prepared by Si ion implantion into SiO2 layers on Si substrate have been measured at room temperature. Their dependence on annealing temperature was investigated in detail. The PL peaks observed in the as-implanted sample originate from the defects in SiO2 layers caused by ion implantation. They actually disappear after thermal annealing at 800 °C. The PL peak from silicon nanocrystals was observed when thermal annealing temperatures are higher than 900 °C. The PL peak is redshifted to 1.7 eV and the intensity reaches maximum at the thermal annealing temperature of 1100 °C. The characterized Raman scattering peak of silicon nanocrystals was observed by using a right angle scattering configuration. The Raman signal related to the silicon nanocrystals appears only in the samples annealed at temperature above 900 °C. It further proves the formation of silicon nanocrystals in these samples. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373836
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  • 3
    Electronic Resource
    Electronic Resource
    Recent progress in optical current sensing techniques (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 3097-3111 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper reviews recent developments in the field of current measurement which employ a wide range of optical and fiber optic techniques. Depending on the current sensing mechanisms involved and the sensing materials used, optical current sensors (OCSs) may be categorized into four main groups: (i) OCSs employing optical fiber as their sensing elements, (ii) OCSs using bulk glass to sense the current, (iii) OCSs using electro-optic hybrid sensing devices, and (iv) OCSs using magnetic field sensing devices. The operational modes of a variety of OCSs have been grouped and discussed, and several examples given. It can be seen that as a result of an intensive and wide ranging research effort using various approaches, substantial progress in the differing aspects of the optical current sensing techniques considered, such as the sensing material used, the configurations of sensing elements introduced, and the detection schemes adapted, has been achieved during the past years. An overall view of the field shows it to be as an active and exciting research area, highlighting several recently introduced and novel sensing materials and configurations which provide impressive results in this field of instrumentation. Examples of applications for the electric power industry are discussed more extensively. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145537
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  • 4
    Electronic Resource
    Electronic Resource
    Photoluminescence studies of type-II self-assembled In0.55Al0.45As/Al0.5Ga0.5As quantum dots grown on (311)A GaAs substrate (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 3188-3190 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigated the photoluminescence (PL) of self-assembled In0.55Al0.45As/Al0.5Ga0.5As quantum dots (QDs) grown on (311)A GaAs substrate. The PL peak at 10 K shifts to lower energy by about 30 meV when the excitation power decreases by two orders of magnitude. It has a red-shift under pressure, that is the character of X-like transition. Moreover, its peak energy is smaller than the indirect gap of bulk Al0.5Ga0.5As and In0.55Al0.45As. We then attribute that peak to the type-II transition between electrons in X valley of Al0.5Ga0.5As and heavy holes in In0.55Al0.45As QDs. A new peak appears at the higher energy when temperature is increased above 70 K. It shifts to higher energy with increasing pressure, corresponding to the transition from conduction Γ band to valence band in QDs. The measurements demonstrate that our In0.55Al0.45As/Al0.5Ga0.5As quantum dots are type-II QDs with X-like conduction-band minimum. To interpret the second X-related peak emerged under pressure, we discuss the X-valley split in QDs briefly. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126624
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  • 5
    Electronic Resource
    Electronic Resource
    Quantitative analysis of excitonic photoluminescence in nitrogen-doped ZnSe epilayers (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 1775-1779 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the photoluminescence (PL) properties of nitrogen-doped ZnSe epilayers grown by molecular beam epitaxy using a nitrogen radio frequency-plasma source. The PL data shows that the relative intensity of the donor-bound exciton (I2) emission to the acceptor-bound exciton (I1) emission strongly depends on both the excitation power and the temperature. This result is explained by a thermalization model of the bound exciton which involved in the capture and emission between the neutral donor bound exciton, the neutral acceptor bound exciton and the free exciton. Quantitative analysis with the proposed mechanism is in good agreement with the experimental data. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369323
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  • 6
    Electronic Resource
    Electronic Resource
    Pressure dependence of photoluminescence in In"xGa"1" "-" "xAs/Al"yGa"1" "-" "yAs strained quantum wells with different widths
    Amsterdam : Elsevier
    Solid State Electronics 37 (1994), S. 885-888 
    Details
    ISSN: 0038-1101
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0038-1101(94)90319-0
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  • 7
    Electronic Resource
    Electronic Resource
    Nitrous oxide and methane transport through rice plants (1997)
    Springer
    Biology and fertility of soils 24 (1997), S. 341-343 
    Details
    ISSN: 1432-0789
    Keywords: Key words Methane ; Nitrous oxide ; Greenhouse gases ; Flooded rice soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The separate closed chamber technique was used to study the potential of rice plants for transporting N2O and CH4 produced in soil to the atmosphere. The results indicate that N2O produced in soil can be conducted to the atmosphere via rice plants similarly to CH4 transport. More than 80% of both N2O and CH4 was emitted through rice plants. The rest was emitted through the soil/water/atmosphere interface by ebullition and diffusion. Nitrate addition increased the total N2O emission rate substantially but decreased the total CH4 emission. Nitrate addition did not change the CH4 emission ratio through rice plants, but lowered the percentage of N2O emission through rice plants. The results suggest that rice plants serve not only as a conduit for most of the CH4 leaving the soil but also for the N2O produced in the soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050254
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  • 8
    Electronic Resource
    Electronic Resource
    Urea N uptake efficiency of ryegrass (Lolium perenne L.) in the presence of urease inhibitors (1993)
    Springer
    Biology and fertility of soils 15 (1993), S. 225-228 
    Details
    ISSN: 1432-0789
    Keywords: Urease inhibitors ; Urea N efficiency ; 15N ; Ryegrass ; Hydroquinone (HQ) ; Phenyl phosphorodiamidate (PPDA) ; N-(n-butyl) phosphorothioic triamide (NBPT)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A greenhouse experiment was conducted to study the comparative efficiency of urea as an N fertilizer with and without the addition of different urease inhibitors. Ryegrass (Lolium perenne L.) was used as the test plant and the N balance technique with 15N was applied. Three urease inhibitors, hydroquinone, phenyl phosphorodiamidate (PPDA), and N-(n-butyl) phosphorothioic triamide (NBPT), were evaluated for their effects on urea-N uptake as well as on grass yield. The addition of urease inhibitors, except for hydroquinone in the later growth period, did not significantly influence the dry matter weight. Throughout the whole growth period, only NBPT significantly increased the total urea-N uptake. In the uninhibited system, the major fertilizer N loss occurred during the first period of grass growth, presumably via NH3 volatilization, since the environment did not favour the other pathways of N loss. However, an appreciable amount of urea N was lost during the later growth period in all inhibited systems, especially in the hydroquinone-treated system. This indicates that the application of urease inhibitors could not eliminate the urea N loss. The greater N loss in the hydroquinone-treated soil appears to be related to the inhibition by hydroquinone of nitrification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00361616
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  • 9
    Electronic Resource
    Electronic Resource
    Methane emission and entrapment in flooded rice soils as affected by soil properties (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 163-168 
    Details
    ISSN: 1432-0789
    Keywords: Greenhouse gases ; Methane emission ; Methane entrapment ; Redox potential ; Rice fields ; Soil organic carbon ; Soil properties ; Soil pH ; Urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Laboratory incubation experiments were conducted to study the effects of soil chemical and physical properties on CH4 emission and entrapment in 16 selected soils with a pH range of 4.7–8.1, organic matter content of 0.72–2.38%, and soil texture from silt to clay. There was no significant correlation with CH4 emission for most of the important soil properties, including soil aerobic pH (measured before anaerobic incubation), total Kjeldahl N, cation exchange capacity, especially soil organic matter, and soil water-soluble C, which were considered to be critical controlling factors of CH4 emission. A lower CH4 emission was observed in some soils with a higher organic matter content. Differences in soil Fe and Mn contents and their chemical forms contributed to the this observation. A significant correlation between the CH4 emission and the soil organic C content was observed only after stratifying soils into subgroups according to the level of CH4 emission in soils not amended with organic matter. The results also showed that the soil redox potential (Eh), anaerobic pH, anerobic pH, and biologically reducible Fe and Mn affected CH4 emission significantly. Urea fertilization promoted CH4 emission in some soils and inhibited it in others. This result appeared to be related to the original soil pH. CH4 entrapment was positively correlated with soil clay content, indicating the importance of soil physical characteristics in reducing CH4 emissions to the atmosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00361401
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