Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    A molecular beam study of alkali promotion of NO sticking on Si(100): Local promotion in a single collision regime (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 3781-3793 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Alkali–metal (K and Cs) promotion for sticking of nitrogen oxide molecule (NO) on Si(100) has been studied using a molecular beam method combined with an Auger electron spectroscopy (AES) and a laser ionization spectroscopy [resonance enhanced multiphoton ionization (REMPI)]. The observed sticking probability S shows a good correlation with alkali coverage, indicating that the alkali promotion is local in nature. The decay of S as a function of NO dose as observed with AES shows an anticorrelation with the evolution of the direct-inelastic scattering intensity as obtained with REMPI. This fact is understood as follows: since the direct-inelastic scattering occurs mostly in a single collision process with the surface, local alkali promotion is realized in a single collision of the incident NO molecule with the alkali–metal adsorbates. The decay of S as a function of NO dose is then analyzed with a reaction cross section. The evaluated reaction cross sections are close to the area of the 2×1 unit cell, and thus the estimated reaction radii are almost equal to but somewhat larger than the covalent radius of a K atom, with a increasing trend with alkali coverage. The alkali promotion is explained in terms of local electron charge transfer from the nonionized alkali adatoms to the affinity level of NO molecules based on the adatom density of state around EF.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462959
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Negative ion production in a large semicylindrical ion source : Proceeding of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2699-2701 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A large semicylindrical negative ion source, whose dimensions are 34 cm in diameter and 104 cm in length, has been developed. By optimizing a chamber depth and a filter strength, a H− current of 650 mA (7.7 mA/cm2) was obtained at an arc condition of 1.3 Pa, 70 V, and 1200 A. In order to increase the H− current and to reduce an operating pressure, a small amount of Cs was injected. As a result, the H− current was increased from 550 mA (6.5 mA/cm2) to 850 mA (10 mA/cm2) under an arc power of 70 V×800 A. The most significant feature of the cesium effect was the reduction of the operating pressure. With maintaining the sufficient current of 670 mA (8 mA/cm2), the operating pressure could be lowered to 0.03 Pa. At this pressure, the highest gas efficiency of 20% was achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142827
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Long pulse operation of a cesium-seeded multicusp H− ion source : Proceeding of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2708-2710 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: It is demonstrated that a cesium-seeded volume H− ion source can be operated very stably for long pulse durations of up to 24 h. The source consists of a 20 cm cylindrical multicusp plasma generator and a 9 cm × 10 cm multiaperture extractor. By seeding a small amount of cesium, the source has produced 50 keV, 0.5 A, 1000 s H− ion beams with a current density of 14 mA/cm2. The cesium effect lasted for more than 24 h once 100 mg cesium was seeded before operation. Power flow measurement revealed that the heat loading of the ion source was low enough to operate the source in the dc mode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142830
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Interferometric measurements of the diameters of a single-crystal silicon sphere (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5320-5325 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new interferometer has been developed for the accurate determination of the density of a silicon crystal, in which a single-crystal silicon sphere of nearly perfect geometry is placed in a Fabry–Perot etalon of accurately known plate distance, and the diameters are obtained by measuring the two gaps between the etalon and the adjacent surface of the sphere. A new method is used to measure the sum of the length of the two gaps by scanning the etalon against the sphere. Two wavelengths, 633 nm from a frequency-stabilized He–Ne laser and 441 nm from a free-running He–Cd laser, are used to determine the order of interference by applying the method of exact fractions. The diameter of about 94 mm has been measured with a resolution of 0.5 nm. Diameter measurements from uniformly distributed directions have shown that the mean diameter has been determined with a standard deviation of 8.6 nm, corresponding to 0.28 ppm in the volume determination. The total uncertainty of the volume is estimated to be 0.34 ppm. Effects of a thin oxide layer and impurities on the bulk density are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143447
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Correlation length of interface roughness and its enhancement in molecular beam epitaxy grown GaAs/AlAs quantum wells studied by mobility measurement (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 1651-1653 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the correlation length (Λ) of interface roughness in GaAs/AlAs quantum wells (QWs) prepared by molecular beam epitaxy (MBE). It is found that the mobility of two-dimensional electrons in very thin selectively doped GaAs/AlAs QW structures is substantially enhanced when the bottom AlAs barrier layer is prepared by alternate beam MBE and/or by the use of superlattice buffer layer below the QW. By measuring the electron concentration dependence of mobility and comparing with the theory of interface roughness scattering, we have found that Λ of the bottom (GaAs-on-AlAs) interface of the QW gets as large as 200–300 A(ring), when prepared by the modified growth technique, which is about three times as large as that (∼70 A(ring)) by conventional MBE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104077
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Atomic-scale morphology and interfaces of epitaxially embedded metal (CoAl)/semiconductor (GaAs/AlAs) heterostructures (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 835-837 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have grown GaAs/AlAs/CoAl/AlAs/GaAs epitaxially embedded metal/semiconductor heterostructures by molecular beam epitaxy. When the growth temperature of overgrown GaAs is relatively low (440 °C), the buried metallic CoAl film with the thickness of 50 A(ring) is uniform and planar with extremely smooth and abrupt metal/semiconductor interfaces. The top (AlAs-on-CoAl) interface is atomically smooth with the roughness of at most 1 monolayer, while the bottom (CoAl-on-AlAs) interface has the roughness of 2–3 monolayers. This sample shows very low resistivity of 11–41 μ Ω cm at room temperature, indicating that the electrically continuous metallic film is grown. In contrast, when the GaAs overlayer is grown at 580 °C, CoAl dots with the size of 200–250 A(ring), which are covered with {001} and {111} facets, are fabricated, resulting from agglomeration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107432
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Role of compressibility on driven magnetic reconnection (1992)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 450-457 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Whether it is induced by an ideal (current driven) instability or by an external force, plasma flow causes a change in the magnetic field configuration and often gives rise to a current intensification locally, thereby a fast driven reconnection being driven there. Many dramatic phenomena in magnetically confined plasmas such as magnetospheric substorms, solar flares, magnetohydrodynamic (MHD) self-organization, and tokamak sawtooth crash, may be attributed to this fast driven reconnection. Using a fourth-order MHD simulation code it is confirmed that compressibility of the plasma plays a crucial role in leading to a fast (MHD time scale) driven reconnection. This indicates that the incompressible representation is not always applicable to the study of a global dynamical behavior of a magnetically confined plasma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860295
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Recovery of bowel motility after high dose fentanyl or morphine anaesthesia for cardiac surgery (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 45 (1990), S. 0 
    Details
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Recovery of bowel function was investigated after cardiac surgery. The time to first passage of flatus was measured using a carbon dioxide analyser as an indication of the return of coordinated bowel motility in 22 adult patients who received high-dose fentanyl (56.3, SD 20.9 μg/kg) or morphine (1.3, SD 0.7 mg/kg) anaesthesia. The time from the patient's arrival in the intensive care unit to passage of the first flatus in patients who received fentanyl anaesthesia was significantly longer than in those who received morphine (p 〈 0.05). There was a significant relationship between the time to first flatus and the total dose of fentanyl, but no such relationship could be demonstrated for morphine. It is concluded that high-dose fentanyl anaesthesia delays recovery of bowel motility in a dose-dependent manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2044.1990.tb14774.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Density relaxation of silicon dioxide on (100) silicon during thermal annealing (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 2195-2198 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Measurements of the refractive index of thermally grown oxide after annealing reveal that the density relaxation of the oxide is well described by a stretched exponential decay function. The experiments of two-step oxidation show that oxygen diffusivity in the oxide exponentially decreases with the oxide density. The relation between the oxide density and the refractive index is well expressed by a simple power relation rather than the Lorenz–Lorenz formula.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345563
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Structure of bis(tri-tert-butylphosphine)palladium(0) (1992)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 48 (1992), S. 739-740 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270191010491
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...