Library

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
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 404-410 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We deposited polymer-like a-C:H films using the plasma-enhanced chemical vapor deposition technique and characterized film microstructure by variable-energy positron lifetime spectroscopy, photoluminescence (PL), and UV-visible absorption spectroscopy. It was confirmed that PL occurs from a chromophore in a sp2 cluster as a result of fast recombination of a photoexcited electron-hole pair. Positron annihilation lifetime spectroscopy showed that positronium (Ps) formation takes place via electron-positron recombination in the sp3 matrix. The lifetime of ortho-positronium (o-Ps) in our a-C:H films was similar to that in polyethylene, indicating their polymer-like nature. The relative PL efficiency increased by about an order of magnitude with increasing film band gap from 1.3 to 3.4 eV, which can be related to the decreasing concentration of nonradiative centers. On the other hand, Ps formation was much less influenced by the band gap and nonradiative centers. Comparison of this result with that for polyethylene mixed with carbon-black nanoparticles, where a considerable reduction in Ps formation was observed, showed that nonradiative centers were of a different nature from the defects on the carbon nanoparticle surface. This work demonstrated the usefulness of positron lifetime spectroscopy combined with optical measurements to study the nanostructure of a-C:H. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 3823-3828 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: ZnSe diodes grown on (100) GaAs substrates by molecular beam epitaxy were investigated using cathodoluminesence (CL) measurements at sample temperatures between 50 and 300 K. The CL line scans at different photon energies were performed on cleaved p–n junctions at 50 and 300 K, respectively. Taking into account surface recombination, carrier generation volume, carrier diffusion and internal built-in electric field and related carrier drift, the CL measurements from cleaved p–n junctions could be qualitatively explained. The charge depletion layer has a strong influence on the CL measurements. The calculated charge depletion width is in good agreement with CL measurements. The experimental data from the spatially resolved CL on the cleaved ZnSe diodes revealed important information of the carrier dynamics and recombination processes in these devices. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 73 (1951), S. 5914-5914 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 75 (1953), S. 4336-4336 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 72 (1950), S. 4887-4890 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 4209-4217 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The first molecular hyperpolarizabilities (β) of a series of charge-transfer nonlinear optical (NLO) chromophores are measured with the hyper-Rayleigh scattering (HRS) technique using two excitation wavelengths at 1064 and 1907 nm. The 1907 nm wavelength is the longest excitation wavelength used for the HRS experiment. For some of these chromophores, β values in excess of 1000×10−30 esu at 1907 nm are obtained, and due to two-photon enhancement, even greater β values are found with the 1064 nm excitation. Chromophores with such large hyperpolarizability are expected to have potential applications in practical electro-optical devices. The dispersion of β is analyzed using a two-vibronic-state model developed previously in our laboratory. The study shows that it is necessary to consider the vibronic structure of the chromophore in the excited state in order to account for the behavior of the first molecular hyperpolarizability of the charge-transfer NLO chromophores. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 2077-2079 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A strong correlation between the surface step structure and phase separation in metastable GaInAsSb epitaxial layers grown by organometallic vapor-phase epitaxy is reported. The full width at half maximum (FWHM) of the 4 K photoluminescence (PL) peak energy is used as a semiquantitative measure of the degree of phase separation: FWHM values increase with phase separation. The step structure of GaInAsSb grown at 525 °C is vicinal, while it is step bunched for layers grown at 575 °C. The corresponding 4 K PL FWHM data indicate smaller FWHM values for layers grown at the lower temperature, and suggest a lower degree of phase separation. Extreme PL broadening is associated with an aperiodic surface structure. Furthermore, the PL FWHM values decrease when the growth rate increases from 1.2 to 5 μm/h. It is proposed that longer adatom lifetimes, which are associated with longer terrace lengths of a step-bunched surface compared to a vicinal one, allow more time for the adatoms to reach equilibrium and thus phase separate. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1942-1944 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the Raman spectra of heavily carbon doped (p〉1019 cm−3) GaSb and GaAsSb. A local vibrational mode (LVM) due to carbon residing on group-V lattice sites was observed at 540 cm−1 for GaSb and 568 cm−1 for GaAs0.44Sb0.56. A gap mode at 164 cm−1 was observed for GaSb. The frequency of the LVM as well as the gap mode is in quantitative agreement with recent theoretical predictions. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 2728-2730 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electrical properties of CdTe and Cd1−xZnxTe crystals grown under excess tellurium by a modified Bridgman technique are critically dependent on the zinc content. Below an x value of 0.07, the as-grown CdZnTe crystals are n type while, above this value, CdZnTe crystals are p type. The origin of the shallow donor level at 0.01 eV below the conduction band is most likely singly ionized Te antisites (Te at Cd sites). The origin of the deep donor level at 0.75 eV below the conduction band is therefore doubly ionized tellurium antisites. Based on this model, the conduction type of CdZnTe crystals is determined by the results of compensation between the shallow donors of Te antisites and the shallow acceptors of Cd vacancies. High resistivity Cd0.9Zn0.1Te crystals are produced by compensating the p-type crystals with indium impurity at a low doping level of 1–5×1015 cm−3. At room temperature, CdZnTe radiation detectors can resolve the six low energy peaks in the 241Am spectrum, a performance comparable to that of the best CdZnTe detectors reported. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 69 (2004), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: : A high-performance liquid chromatography/evaporative light scattering detection (HPLC/ELSD) method was developed to determine natural forms of soyasaponin B with (αg, βg, βa, γg, γya) and without (V, I, II, III, IV) 2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP) in soybean. The coefficient of variance of intra-day assays was 〈 9.51% and that of inter-day assays was 〈 10.91%. The soyasaponin I was used as external standard for quantification of all soyasaponins because it was established that their ELSD signal responses were essentially the same under the specific operating conditions. The extraction conditions were optimized and the extract storage conditions were established for analysis of soyasaponin Bs in their natural state. The energy of activation of soyasaponin Pg was 40.76 kJ/mol. The recovery rates for soyasaponin I and II were 98.3% and 93.1%, respectively. The average of total soyasaponins content from 5 soybean samples was 3.37 μmol/g with ranges from 2.78 to 4.03 μmol/g. This method is simple and easy to use, and the sample preparation takes less time than existing methods.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...