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  • 1
    Electronic Resource
    Electronic Resource
    Tunnel spectroscopy of the AlGaAs-GaAs heterostructure interface (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1112-1114 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The material interface of a molecular beam epitaxy grown Al0.5Ga0.5As-GaAs heterostructure is investigated on a cross-sectional (110) cleavage plane using tunnel spectroscopy. The depleted n-type region and the electron confinement layer adjacent to the interface are identified with local current-voltage spectroscopy. The spatial width of these layers is close to 15 nm. The spectroscopy can be interpreted with the valence-band offset in the interface, and a value of 0.35 eV is found for this quantity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100773
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  • 2
    Electronic Resource
    Electronic Resource
    Calculation and measurement of initial electron densities in x-ray preionized avalanche discharge lasers (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 4521-4528 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The initial electron density in x-ray preionized avalanche discharge lasers has been studied extensively. A computer model has been developed to calculate this initial electron density taking into account the characteristics of the x-ray source, x-ray physics, and geometric effects. Results of these calculations were verified for various experimental conditions using an ionization chamber. The experimental data are in excellent agreement with the calculations. Results from this work may be directly applied in the design of x-ray preionized gas lasers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343248
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  • 3
    Electronic Resource
    Electronic Resource
    High-stability scanning tunneling microscope (1985)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 1573-1576 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have constructed a scanning tunneling microscope for operation under UHV conditions (10−8 Pa). With this instrument topographic measurements can be made on metal and semiconductor surfaces by means of a scanning tip electrode, driven by piezoelectric ceramic elements. The maximum area covered ranges up to 4000×4000 A(ring)2 with a resolution better than 10 A(ring) laterally and 0.15 A(ring) rms perpendicular to the plane. Because of its compact design, the scan unit is very insensitive to vibrations and has a response time down to 0.3 ms. This allows a high scan rate to be used. In order to minimize temperature effects, special attention is paid to the geometry of the construction and the materials used, resulting in a drift ≤4 A(ring)/min along the surface and 0.5 A(ring)/min perpendicular.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138155
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  • 4
    Electronic Resource
    Electronic Resource
    A low temperature scanning tunneling microscope for use in high magnetic fields (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 4146-4149 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe the design and performance of a low temperature (1.3–4.2 K) scanning tunneling microscope (STM) setup that can be used in magnetic fields up to 9.5 T. Due to the compact, rigid, and concentric design, the STM is very insensitive to external vibrations. The influence of external magnetic fields on the performance of the STM has been minimized by making a version completely out of titanium (instead of stainless steel). The STM routinely shows atomic resolution on various samples over the whole magnetic field range. We demonstrate the spectroscopic capability by local spectroscopy of the Abrikosov flux lattice on NbSe2. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146492
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  • 5
    Electronic Resource
    Electronic Resource
    Spectrally resolved luminescence from an InGaAs quantum well induced by an ambient scanning tunneling microscope (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 3656-3658 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spectrally resolved scanning tunneling microscope-induced luminescence has been obtained under ambient conditions, i.e., at room temperature, in air, by passivating the sample surface with sulfur. This passivation turned out to be essential to suppress the local anodic oxidation induced by the tunneling current. From the dependence of the luminescence signal on tunneling current and voltage, we find that the passivation solution and post-passivation annealing temperature strongly modify the surface density of states (SDOS). More specifically, we found evidence that, after annealing at 400 °C, no SDOS is left above the bottom of the conduction band. For annealing at 200 °C, the SDOS is found to be extended up to 1.0±0.2 eV above the bottom of the conduction band. In all cases, the passivated (001) surface appears to be completely pinned. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125419
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  • 6
    Electronic Resource
    Electronic Resource
    Molecular spectroscopy of dye aggregates by scanning-tunneling-microscope-induced light emission (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 527-529 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A bromide-modified silver (111) surface, covered by Jelly-type aggregates of a cyanine dye, is investigated by scanning tunneling microscopy (STM) in air. We show that, under appropriate conditions, light is emitted out of the junction by inelastic electron tunneling. Study of the relation between the light intensity and the tunnel bias clearly reveals a molecular influence on the light emission. Furthermore, through a spectral analysis, we show that sharp resonances appear for dye-covered surfaces by coupling of tip-induced plasmons with molecular excitations. This demonstrates that through STM-induced luminescence local spectroscopic information can be obtained on molecules. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1383570
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  • 7
    Electronic Resource
    Electronic Resource
    High-efficiency operation of a gas discharge XeCl laser using a magnetically induced resonant voltage overshoot circuit (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 3517-3519 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An electrical to optical efficiency of 5% has been demonstrated in an x-ray preionized XeCl discharge laser using an improved prepulse-mainpulse circuit, based on resonant charging of the peaking capacitor. In contrast to known prepulse-mainpulse circuits, the new scheme has no time delay between prepulse and mainpulse nor a voltage reversal on the electrodes. We present three possible configurations of the scheme and one of them has been realized for demonstrating its high-efficiency capabilities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345343
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  • 8
    Electronic Resource
    Electronic Resource
    Mixture-dependent electron densities in x-ray preionized Ne-Xe-HCl mixtures (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 2716-2724 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Preionization electron densities have been studied in an x-ray preionized XeCl laser as a function of the gas composition. Also the influence of emission of photoelectrons from the electrode surfaces on the initial electron density has been determined. For low Xe partial pressures, an excited neon bottleneck in the Penning ionization process of Xe is found. For higher Xe pressures, the preionization density increases linearly with the Xe concentration. A simple model gives a satisfactory agreement with the measurements over more than two decades of Xe partial pressure. We also determine the density of Ne* following x-ray irradiation. Measurements in mixtures containing HCl show that due to electron attachment no initial value of the electron density can be assigned. The method used here will give a lower estimate for the total charge density in these mixtures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345460
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  • 9
    Electronic Resource
    Electronic Resource
    Dextran sedimentation induces a difference in the percentage of hypodense eosinophils in peripheral blood between children with allergic asthma and healthy controls (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 24 (1994), S. 0 
    Details
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Considerable differences in the percentage of hypodense eosinophils in the peripheral blood of asthmatics have been reported by different investigators. In these previous studies dextran sedimentation was used for removal of erythrocytes prior to density centrifugation. We hypothesized that the sedimentation procedure might induce the presence of hypodense eosinophils in the peripheral blood of asthmatic patients. In order to test this hypothesis, we compared eosinophil density profiles from peripheral blood of children with asthma and of age-matched healthy controls, using different procedures. In the first method (direct method) blood samples were directly layered on a discontinuous Percoll gradient. Erythrocytes were removed by isotonic lysis. In the second method (dextran sedimentation) erythrocytes were removed by sedimentation with dextran prior to gradient centrifugation. Results of the direct method show no significant difference in percentage of hypodense eosinophils between children with asthma and healthy controls (9.19% and 6.84% respectively). However, after dextran sedimentation, children with asthma had a significantly higher percentage of hypo-dense eosinophils than healthy controls (15.40% and 8.84% respectively; P 〈 0.05). The percentage of hypodense eosinophils was correlated with the number of eosinophils and with the lung function, measured as the Tiffeneau index (FEV1/VC), in the whole group of subjects when the direct method was used. We conclude that an increased percentage of hypodense eosinophils is not present in the circulation of children with asthma, but can be induced in vitro by dextran sedimentation. Therefore, in vitro generation of hypodense eosinophils in the blood of patients with asthma seems to be related with the primed state of eosinophils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2222.1994.tb02730.x
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  • 10
    Electronic Resource
    Electronic Resource
    Risk factors for atopic dermatitis in infants at high risk of allergy: the PIAMA study (2003)
    Oxford, UK : Blackwell Science Ltd
    Clinical & experimental allergy 33 (2003), S. 0 
    Details
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background It has been suggested that the period immediately after birth is a sensitive period for the development of atopic disease.Objective We investigated whether birth characteristics and environmental factors are associated with the development of atopic dermatitis in the first year of life.Methods Seventy-six children with and 228 without atopic dermatitis, all children of mothers with respiratory allergy or asthma (PIAMA birth cohort study) were included in the study. Atopic dermatitis was defined as a positive history of an itchy skin condition with at least two of the following characteristics: visible dermatitis, history of outer arms/leg involvement, or general dry skin. Multiple logistic regression analysis was performed to study the independent effects of various risk factors.Results A birth weight 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:09547894:CEA1751:ges" location="ges.gif"/〉4000 g compared to 3000–4000 g was a significant risk factor for atopic dermatitis (odds ratio (OR)=2.4; 95% CI: 1.1–5.1) as was day care attendance (OR=2.9; 95% CI: 1.5–5.9). Exclusive breastfeeding in the first 3 months was negatively associated with atopic dermatitis (OR=0.6; 95% CI: 0.3–1.2), especially with visible dermatitis (OR=0.4; 95% CI: 0.2–1.0). Gender, gestational age, the presence of siblings or pets, and parental smoking were not significantly associated with atopic dermatitis.Conclusion This study shows that a high birth weight and day care attendance increase the risk of atopic dermatitis in the first year of life, while exclusive breastfeeding is a protective factor when dermatitis is found on inspection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2222.2003.01751.x
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