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 88 (2000), S. 6382-6387 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured far-infrared and infrared reflectivity as well as Raman scattering in an [(InP)5(In0.49Ga0.51As)8]30 superlattice grown by molecular beam epitaxy. A numerical model for calculating the reflectivity coefficient for complex systems which includes superlattice, buffer layer, and substrate has been developed. The far-infrared reflectivity spectra consists of the superlattice confined and interface modes as well as the modes from the buffer layer (In0.49Ga0.51As) and the substrate (InP). In the infrared spectral range above 1000 cm−1 we observe only interference fringes from the buffer layer. A good agreement between calculated and experimental spectra is achieved. The folded longitudinal acoustic phonon doublet appears at about 39 cm−1 in the Raman scattering spectra. The frequency agrees well with a continuum model calculation. In the optical phonon spectral region we observe confined modes corresponding to both constituents. The modes representing vibrations of atoms at both interfaces: InP/InGaAs (230 cm−1 mode) and InGaAs/InP (240 and 260 cm−1 modes) have also been observed. The geometrical parameters of the sample, obtained from the fitting of the reflectivity data, agree well to the values of the layer thickness obtained by double crystal x-ray diffraction. © 2000 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
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 846-848 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The short-period (GaAs)n1(AlAs)n2 superlattices with parameters (n1,n2)=(21,25), (6,42), (14,16), and (23,8) have been grown by molecular beam epitaxy on GaAs substrates along the [012] direction and characterized by x-ray and Raman scattering spectroscopy. The appearance of distinct satellite peaks around the Bragg reflections demonstrates the formation of high quality superlattices. The observed TO and LO confined modes have frequencies which map closely those of the optical phonons of bulk GaAs and AlAs in the Γ-W-X direction.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aims: No study has directly compared different histomorphometric methods of quantification of myocardial fibrosis. Therefore we compared the results of semiquantitative, point-counting and computer-based methods in the assessement of myocardial fibrosis in a consecutive series of endomyocardial biopsy samples from patients with heart muscle disease.Methods and results: Histological samples (at least three per patient) were obtained by endomyocardial biopsy from 11 patients with focal myocarditis and from 24 ambulatory patients with idiopathic dilated cardiomyopathy, or during surgery in 10 patients who underwent partial left ventriculectomy. Samples were cut and stained with Masson-trichrome for better contrast. From each sample, a representative field was digitized, and the amount of fibrosis was assessed by semiquantitative scoring, by point-counting, and by computer-based software. Semiquantitative scoring correlated with both point-counting (Spearman's r = 0.69, P 〈 0.0001) and computer-based (Spearman's r = 0.83, P 〈 0.0001) methods. There was also a good correlation between point-counting and computer-based methods (r = 0.71, P 〈 0.0001). However, when compared with the point-counting method, the computer-based method overestimated percent fibrosis by 3.0 ± 6.7% (P = 0.004). This overestimation correlated with the mean percent fibrosis (r = 0.38, P = 0.014).Conclusions: Our data show good correlations between the three methods of myocardial fibrosis assessment. However, systematic differences between them emphasize that this should be taken into consideration when comparing results of the studies using different methods of fibrosis assessment.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 94 (1994), S. 261-264 
    ISSN: 1434-6036
    Keywords: 74.25.Gz ; 74.25.Ke ; 78.30.Er
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Here we present Raman spectra of YBa2(Cu1−x Zn x )3O7 and YBa2(Cu1−x Ni x )3O7 as a function of temperature and Zn or Ni content. The temperature dependence of two modes at 340 and 440 cm−1 is analyzed. Similarly to the infrared measurements it is found that Zn substantially suppresses the superconductivity induced phonon softening whereas, Ni does not affect much that effect. Moreover, the superconductivity induced phonon stiffening of the 440 cm−1 mode completely disappeared with the Zn doping. We find this behaviour might support the model where Zn acts effectively as a magnetic pair breaker.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 72 (1988), S. 13-16 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report both Raman and infrared reflectivity spectra of M2Cu2O5 (M=Y, Ho) at room temperature in the spectral range of 30–1000 cm−1.37 (31) ir and 18 (15) Raman active modes of Y2Cu2O5 (Ho2Cu2O5) are observed. A factor group analysis has been performed to identify the symmetries of the observed modes. Comparing the vibrational spectra of these compounds we conclude that the phonons above 300 cm−1 originate from the Cu−O vibrations and those under 300 cm−1 from M−O vibrations.
    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...