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  • Articles  (26)
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  • Articles  (26)
Journal
  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 2659-2660 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The surface plasmon enhancement effect on adsorbed molecules at elevated substrate temperatures is studied theoretically using surface enhanced Raman scattering (SERS) as an example. The surface structure is idealized to be a monodisperse spherical particle with its nonlocal dielectric response accounted for. The temperature effects are modeled using a temperature-dependent collision frequency in the Drude model. Numerical results show that only a small decrease in the SERS enhancement ratio occurs for temperatures up to the melting point of the substrate, even for scattering close to the surface plasmon resonance frequency of the metal. More definitive results are subjected to more realistic modeling as well as systematic experimental studies. The implication of this result to other surface photochemical processes is discussed. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 3599-3606 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The spectral band profiles of the E¯→4A2g and 2A¯→4A2g transitions of Cr3+ in Al2O3, i.e., the commonly known ruby 6943 A(ring) (R1) and 6929 A(ring) (R2) emission lines, in the temperature range 10–300 K were recorded and deconvoluted numerically with excellent accuracy into a Lorentzian (homogeneous) component and a Gaussian component. The Gaussian width was taken as arising from sample inhomogeneity and spectrometer slit function, and as expected was found to be independent of temperature. The Lorentzian width was found to vary with temperature in accordance with the two-phonon relaxation processes reported previously, plus a thermal broadening process. While the former processes were quenched completely as temperature was lowered to about 90 K, the latter process, describable with the Debye–Waller factor, still caused a Lorentzian width of about 0.2 cm−1 (for both R1 and R2 lines) which then leveled out quickly to about 0.1 cm−1 as the temperature was lowered further. For temperatures above 100 K, the positions of the R1 and R2 lines were found to have the same temperature dependence as that reported previously. The use of the temperature dependencies of Lorentzian width and line position for temperature sensing was discussed; such an instrument could indeed be made portable because of the simple optical and electronic systems used in our experiments.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 3746-3748 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Raman studies of Li0.02Na0.98NbO3 ceramics were observed in the temperature range between 10 and 300 K. The spectral pattern evolves gradually at a transition temperature (130–170 K) in the cooling process and then changes suddenly near 280 K on heating. The observed thermal hysteresis of 110 K and also the transition temperatures agree well with evidence coming from the differential scanning calorimetric, the dielectric constant, and the thermal expansion measurements. The observed spectra are discussed following the separation of modes into internal stretching modes of the NbO6 octahedron and cation translation modes. The 62- and 74-cm−1 peaks are proposed due to the translational modes of Na+ cation.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Applied Surface Science 33-34 (1988), S. 212-219 
    ISSN: 0169-4332
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Surface Science Letters 251-252 (1991), S. A341 
    ISSN: 0167-2584
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 49 (1989), S. 285-292 
    ISSN: 1432-0630
    Keywords: 73.40 ; 82.80 ; 85.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract UV(He I) and X-ray photoelectron spectroscopies (UPS and XPS) were used to examine the alloying behavior of AuGe ohmic contacts to silicon-doped 〈100〉 oriented n-type GaAs substrates. The reacted interface was then revealed by Ar ion sputter depth profiling at room temperature and after annealing in ultra high vacuum at 300°, 500°, or 700°C. The indiffusion of Au and the outdiffusion of Ga and As are evident. Instead of obtaining a maximum peak of the Ge profile on annealing in forming gas, we observed an increase of Ge indiffusion with temperature. The Au indiffusion results in a decrease in the Au 5d splitting and a shift of both levels to higher binding energy. Au-Ga alloy formation is indicated by the Au 4f levels, and is further supported by the observation of the metallic Ga peak. It has been concluded that the sample annealed at 500°C forms the Au-Ga alloy and the compound of As containing Ge more easily than the samples annealed at 300° or 700°C. This result is consistent with the observations of low contact resistance at the annealing temperature of ∼ 500°C for AuNiGe ohmic contacts to n-type GaAs.
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  • 7
    ISSN: 1432-0630
    Keywords: 73.40 ; 82.80 ; 85.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract An ultra-thin AuGeNi alloy (84%/12%/4% by weight) overlayer of 5 nm was evaporated onto Te-doped n-type (100) oriented GaSb substrates. Samples were annealed in ultra-high vacuum (UHV), with a base pressure of 10−10 Torr at either 300°C, 500°C, or 700°C for 12 h. The reacted interface was then revealed by Ar ion sputter-depth profiling. The highest percentage of Ge in the deep interface region was observed for the sample annealed at 500°C. Annealing at 500°C also leads to a uniform distribution of Ga, Sb, and Au concentrations. Results show that virtually all Au, Ge, and Ni evaporate away after annealing at 700°C. Au-based AuGa alloy formation was indicated by the shifts of Au 4f core-levels and the metallic Ga 3d peak. The small variation of Au 4f core-levels with sputtering for samples annealed at 500°C is the evidence of AuGa uniform alloying from the surface to the interface. It has been, therefore, concluded that annealing at 500°C forms a more uniform distribution of cluster size throughout the interface than annealing at 300°C or 700°C.
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 22 (1991), S. 333-337 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Raman spectra of a series of MgO-doped congruent LiNbO3 crystals were obtained with MgO concentrations up to 30 mol.%. Single crystals were successfully grown and no precipitates were discovered. The intensity, frequency and line width of the Raman phonons were studied as a function of doping percentage. An abrupt change was observed near the composition of 7.5 mol.% of MgO-doped LiNbO3 crystal. From the spectral changes it is proposed that Mg2+ replaces the mis-sited Nb5+ cation at Li sites first. When these mis-sited Nb5+ cations have been completely replaced, the Mg2+ cation then replaces the Li+ cation and creates vacancies at Li+ sites.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 24 (1993), S. 179-181 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Good-quality high-Tc YBa2Cu3O7-x thin films deposited by the laser ablation method were investigated by Raman spectrosocpy. The vibrational spectra of thin films of YBa2Cu3O7-x at various laser intensities and with different polarizations were measured. The Raman modes change on increasing the laser power and in general such changes are reversible. However, as the laser intensity is increased above a certain value, dramatic changes occur in the Raman peaks, as a result of damage to the sample.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 15 (1984), S. 51-54 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The vibrational spectra of polycrystalline samples of titanium and tin tetrachlorides at 80 K have been investigated by Raman spectroscopic techniques. In the intramolecular region, isotopic and crystalline field splittings are observed, in substantial agreement with earlier work. In the lattice region, ten of the twelve Raman-active lattice modes are observed. A simple model is suggested and used to distinguish the low-frequency lattice translational from librational modes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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