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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Electroanalytical Chemistry 356 (1993), S. 245-253 
    ISSN: 0022-0728
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Tetrahedron Letters 9 (1968), S. 6091-6094 
    ISSN: 0040-4039
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Sensors and Actuators B: Chemical 14 (1993), S. 752-753 
    ISSN: 0925-4005
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 5094-5105 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A rapid optical absorption change is observed in a GaAs/AlAs short-period superlattice having Wannier–Stark localization. This phenomenon is clearly explained by a rapid collapse of Wannier–Stark localization due to electric field screening by photogenerated space charges. The screening causes a positive feedback loop between restoration of the blue-shifted wavelength of the absorption band-edge towards the red and an increase in optical absorption, which causes an additional field screening. The experimental bias voltage dependence of the intensity of photoluminescence and photocurrent under high optical excitation, agree well with a model applying Fowler–Nordheim tunneling at the heterointerface cladding layer. It is concluded that the space charges are stopped near the cladding layer and that the superlattice region is almost fully screened to near the flat-band bias condition. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 2957-2973 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Fibrous and crystal structures of a helical polymer, poly-L-lactic acid (PLLA), were analyzed by using x-ray diffraction experiments. It was confirmed that the molecular residues were arranged on a nonintegral 10/3 helix as De Santis and Kovacs [Biopolymers 6, 299 (1968)] reported. The atomic positions in a monomeric unit, which were proposed by Hoogsteen, Postema, Pennings, ten Brinke, and Zugenmaier [Macromolecules 23, 634 (1990)], were validated. However, the previous reports on the positions of the two helical chains were found to be in error. The correct positions were determined. The second helical chain shifts from the base center by 0.45, 0.25, and 0.61 A(ring) along a, b, and c axes. Besides, the second chain rotates by 2.46° with respect to the first. Distribution function of the crystallites in various drawn fibers were determined as a function of spiral angle. Optical gyrations of PLLA and poly-D-lactic acid fibers were successfully measured by using high accuracy universal polarimeter, as functions of temperature and drawing ratio. By using x-ray data of the change of the fibrous structure by drawing treatments, the gyration tensor components of PLLA could be calculated. It is of great interest that gyration tensor component g33 along the helical axis is extremely large, ∼(3.85±0.69)×10−2, which corresponds to a rotatory power of (9.2±1.7)×103°/mm, about two orders of magnitude larger than those of ordinary crystals. This is the first experimental evidence that helical polymers will produce enormous optical activity in the solid state. Helical polymers will be important for the elucidation of gyro-optical properties of solids and promising for new optical applications utilizing their large optical activity. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 5915-5920 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Unstrained InGaAs (4.5 nm)/InAlAs (1.0 nm) short-period superlattices grown on a (100) GaAs substrate were studied. To achieve this growth, an In-composition-graded buffer layer and a thick InGaAs buffer layer were adopted. Structural properties were investigated by x-ray diffraction, atomic force microscopy, and a compositional analysis by the thickness fringe method. X-ray diffraction patterns showed clear periodicity in the superlattices and atomic force spectroscopy images showed cross-hatch morphology for the main ridge along the (011¯) direction. Clear thickness fringes in the bright-field electron microscope images for the superlattice region and ambiguous fringes for the graded buffer layer indicate that misfit dislocation due to lattice mismatch concentrates in the graded buffer and a high-quality superlattice is successfully grown in spite of the large lattice mismatch between the superlattice and the substrate. Optical characteristics measured by photocurrent spectroscopy reveal a clear Wannier–Stark localization effect at room temperature. The experimental absorption energies agree well with calculated values by a transfer matrix method using parameters for bulk InGaAs and InAlAs. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 2285-2290 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the observation of the Wannier–Stark localization effect in short period GaAs/ InXAl1−XAs superlattices with strained barriers. The superlattices, each of which is contained in the intrinsic region of a p-i-n diode structure, consist of GaAs (3.0 nm) wells and strained shallow InXAl1−XAs (0.9 nm) barriers (X=0, 0.1, 0.2, and 0.3) grown on GaAs by molecular beam epitaxy. In spite of the use of strained barriers, the Wannier–Stark localization effect is clearly observed for all samples at room temperature. Even the superlattice sample with the highest In content of X=0.3 exhibits distinct photocurrent spectra showing several peaks associated with Wannier–Stark ladder transitions as well as Franz–Keldysh oscillations. It is found that the transition intensities are consistent with theoretically calculated oscillator strengths based on the simplified tight-binding model. By increasing the In content X, the miniband width increases and the absorption peak energy due to the zeroth order ladder (e1-hh1 and e1-lh1) transitions decreases because of the reduced barrier height. The transition energies are consistently explained by taking modulation effects into account on the valence subbands due to the compressively strained barriers. The above results show that the use of a large strain effect on the barriers is possible in Wannier–Stark localization effect type devices. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 7273-7281 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Generation of extra facets on ridge-type triangles with (001)-, (110)-, and (201)-related equivalent slopes on GaAs (111) A substrates and stripes running in the [1¯10], [110], and [100] directions on (001) substrates during molecular beam epitaxy of GaAs/AlGaAs multilayers was investigated. By investigating local variation in layer thickness in the regions adjacent to extra (114)A, (110), and (1¯1¯1¯)B facets common to the (111)A and (001) patterned substrates and extra facets specific to the respective substrates and growth rates of the facets relative to the growth rate on the substrate plane, the orientation-dependent Ga surface diffusion length, λGa, was elucidated as λGa(001)(approximate)λGa(1¯1¯3¯)B〈{λGa(1¯1¯1 ¯)B,λGa(3¯3¯1¯)B,λGa(013),λGa(113)A}〈λGa(159)(approximate)λGa(114)A(approximate)λGa(111)A〈λGa(110). That is, λGa increases in the order of the (001), (1¯1¯1¯)B-related, (111)A-related, and (110) surfaces.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    International journal of cosmetic science 27 (2005), S. 0 
    ISSN: 1468-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Three-dimensional structural analyses of human hair fibers and comparison of the different fibers were tried by using the Ultra-high Voltage Electron Microscope (UHVEM). The analysis condition, sample preparation, and a machine state were adjusted to the suitable condition for tilting observation of from –70° to +70°, at 2° intervals. The tomography of hair fiber was successfully reconstructed from the different angle pictures with IMODE software in a computer. By using UHVEM, the various human hair fibers from Japanese and Caucasians were investigated and discussed about their structures.
    Type of Medium: Electronic Resource
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