Bibliothek

feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • 1985-1989  (4)
  • 1930-1934
  • 1987  (4)
Materialart
Erscheinungszeitraum
  • 1985-1989  (4)
  • 1930-1934
Jahr
Schlagwörter
  • 1
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 226-228 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The trapping efficiency and trapping dynamics of photoexcited carriers in GaAs/AlGaAs single quantum wells with different confinement structures are examined at low temperature by means of picosecond luminescence as well as photoluminescence excitation spectroscopy. The trapping efficiency is 100% only in graded-index separate confinement heterostructures with a linear band-gap profile. The lower trapping efficiency of other confinement structures is due to radiative and nonradiative recombination in the confinement layers.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1717-1719 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: By investigating the linear polarization dependence of intrinsic emissions from undoped GaAs/AlAs short-period superlattices at room temperature, it is shown that a dominating peak observed in the normal emission spectra is due to the free-carrier recombination associated with the lowest electron to mixed-hole subbands with an unexpectedly large light-hole character instead of with the lowest electron to pure heavy-hole subbands expected in an ideal superlattice. Origins of the extensive valence-band mixing in the synthesized superlattices are discussed in relation to microscopic fluctuations in the layer thicknesses observed in the transmission electron microscope lattice image.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    ISSN: 1432-0630
    Schlagwort(e): 78.65.-s ; 73.20.Dx ; 78.55.-m ; 73.60.Br
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Excitonic resonance structures in GaAs/AlAs multiple quantum well heterostructures with varying barrier-layer thicknessesL B down to 1.3 nm are investigated for two sets of samples with the nominal well widths ofL Z =9.2 and 6.4 nm, by 2K photoluminescence excitation spectroscopy. The observed resonance energies of then=1 heavyhole (1 hh) and light-hole (1 lh) free excitons imply that quantum confinement effects persist at least down to the decreased barrier-layer thickness ofL B =1.3 nm. This result is inconsistent with the red shifts expected from the simple well-coupling theory within the one-band Kronig-Penney model at theГ point. Instead, blue shifts of 6–8 meV (8–17 meV) are observed for the 1 hh (1 lh) excitonic resonance peaks whenL B is decreased from 10 to 2 nm. A relative decrease of the oscillator strength of the 1 lh transition compared to the 1 hh transition is also observed asL B is decreased. These results manifest important effects of the indirect-gap barrier material for the actual wavefunction matching across the interface and the breakdown of the envelope function approach to GaAs/AlAs quantum well heterostructures with ultrathin barriers.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    ISSN: 1573-6865
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Polyamines are low molecular weight organic cations, necessary for cell proliferation and implicated in numerous biochemical events. Their light microscopical distribution has previously been studied by the use of two fluorescence cytochemical methods. With the aid of an antibody recognizing the two main polyamines, spermidine and spermine, we now report on their immunocytochemical localization in animal tissues. Polyamine immunocytochemistry was found to require very well controlled conditions of fixation in order to prevent diffusion, loss and redistribution of endogenous polyamines. Moreover, in certain cellular compartments, polyamine immunoreactivity was masked by proteins, necessitating proteolytic pretreatment of sections prior to staining. The fluorescence cytochemical methods, employing low molecular weight reagents, did not require such unmasking. The results of the optimized immunocytochemical procedure were in complete agreement with the results obtained by the fluorescence cytochemical methods. Although fluorescence cytochemistry, is simpler and quicker to perform than immunocytochemistry, the latter technique may be extended to studies of polyamines at the ultrastructural level.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...