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  • 79.60  (5)
  • ZnSe  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Radiative and non-radiative decays from the excited state of Ti3+ ions in oxide crystals (1990)
    Springer
    Applied physics 51 (1990), S. 329-335 
    Details
    ISSN: 1432-0649
    Keywords: 42.70 ; 79.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The fluorescence spectra of Ti3+ in Y3Al5O12 (YAG), Al2O3 (sapphire), YAlO3 (YAP) observed at 10 K are composed of zero-phonon lines accompanied by the broad vibronic sidebands. The temperature dependence of the fluorescence lifetime and of the total intensity of the broadband measured in YAG and Al2O3 indicate that the radiative decay times from the excited states are nearly constant in the range 10–300 K. This demonstrates that the broadband radiative emissions in Ti3+:YAG and Ti3+:Al2O3 are due to magnetic dipole transitions or to electric dipole transitions induced by static odd-parity distortion, respectively. The decrease of the fluorescence lifetime with increasing temperature in Ti3+:YAG and Ti3+:Al2O3 is due to non-radiative decay from the excited state which occurs through phonon-assisted tunnelling between the excited and ground states. The radiative decay of Ti3+:YAP is enhanced with increasing temperature, indicating that radiative decay rate contains a term associated with odd-parity phonons. Nevertheless, a non-radiative decay rate of 3.6 × 104 s−1 observed in the temperature range 10–300 K is due to excited state absorption, which depopulates the excited state and quenches the fluorescence at the laser wavelength.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348969
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Polarization of emission spectra from Ti3+-Doped oxide crystals (1991)
    Springer
    Applied physics 52 (1991), S. 122-131 
    Details
    ISSN: 1432-0649
    Keywords: 42.55R ; 42.70 ; 79.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The photoluminescence spectra of Ti3+-doped YAlO3, Y3Al5O12 and Al2O3 crystals display weak zero-phonon lines and broad vibronic side bands. The zero-phonon lines are due to the splitting of the 2 T 2g ground state into three Kramers' doublets by the combined effects of static axial crystal field, Jahn-Teller effect and spin-orbit interaction. A molecular orbital method is used to calculate the relative intensities and polarizations of both zero-phonon lines and broad band in terms of the mixing of odd-parity ligand wavefunctions into even-parity Ti3+ wavefunctions by odd-parity crystal fields of T 1u and T 2u symmetries at sites with tetragonal and trigonal symmetries. The odd-parity distortions may be static or dynamic and are of crucial relevance in determining the strength of vibronically induced transitions. In general, selection rules for optical spectra are uniquely determined by group theory. The relevance of the molecular orbit description of the d-d transitions is that it permits a physical interpretation of the strength of optical spectra in terms of the covalent charge transfer from ligand ions to central ions induced by odd-parity crystal field distortion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00357666
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Polarization of emission spectra from Ti3+-doped oxide crystals (1991)
    Springer
    Applied physics 52 (1991), S. 225-229 
    Details
    ISSN: 1432-0649
    Keywords: 42.55R ; 42.70 ; 79.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Ti3+ ion in YAlO3 (YAP), Y3Al5O12 (YAG), and Al2O3 crystals occupies distorted octahedral sites relative to the nearest neighbour ligand ions. Such distortions are of even-parity in YAG where the zero-phonon lines in emission occur via magnetic dipole transitions. In contrast, the zero-phonon transitions occur by electric dipole processes in Ti3+:YAP and Ti3+:Al2O3 where there are odd-parity distortions from octahedral symmetry. This paper reports measurements of the zero-phonon lines of Ti3+ ions in YAP, YAG, and Al2O3 at 10 K. The zero-phonon lines of Ti3+:YAP are strongly polarized perpendicular to the tetragonal axis and those of Ti3+:Al2O3 parallel to the trigonal axis. The experimental results are shown to be in accord with a molecular orbital model of the radiative transition according to which the transition intensities derive from odd-parity ligand wavefunctions induced into even-parity ground and excited Ti3+ wavefunctions by odd-parity crystal distortions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750955
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Temperature dependence of the lifetime of Cr3+ luminescence in garnet crystals I (1990)
    Springer
    Applied physics 50 (1990), S. 425-431 
    Details
    ISSN: 1432-0649
    Keywords: 42.70 ; 79.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The lifetimes of the R-lines from the 2 E level and the broad bands from the 4 T 2 level of Cr3+ ions in various garnet crystals vary with the energy separation between the 2 E and 4 T 2 levels, which change systematically with the composition of host crystal. The trend of the Cr3+ lifetimes, as well as their temperature dependences in garnet crystals, is explained by zero-point vibration and phonon-assisted tunnelling between the 2 E and 4 T 2 states of Cr3+ ion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325096
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Temperature dependence of the lifetime of Cr3+ luminescence in garnet crystals (1990)
    Springer
    Applied physics 51 (1990), S. 132-136 
    Details
    ISSN: 1432-0649
    Keywords: 42.70 ; 79.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The coexistence of sharp R-lines from the 2 E state and the broad band from the 4 T 2 state in the photoluminescence spectra of Cr3+:Gd3Sc2Ga3O12 (GSGG) and Cr3+:Y3Ga5O12 (YGG) is observed at low temperature (10K). The decay lifetimes of the broad emission bands of Cr3+ in GSGG and YGG are very close to those of the R-lines being, respectively, 0.23 ms and 2.5 ms. These results are explained in terms of the extent of the mixing of the 4 T 2 vibronic wavefunction with that of the 2 E lowest excited state by tunnelling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326013
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Depth-resolved cathodoluminescence of ZnSe epilayers (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 295-299 
    Details
    ISSN: 1057-9257
    Keywords: Cathodoluminescence ; Strain ; ZnSe ; Depth profiling ; Defects ; Impurities ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: In This paper we illustrate the use of an electron beam of variable energy to get depth information on the strain, impurity and defect distribution in ZnSe epilayers. From the increase in splitting of the free light and heavy hole exciton bands with increasing electron beam energy we deduce that the strain increases with depth. From the increase in the luminescence intensity of the impurity and defect bands compared with the luminescene intensity of the free heavy hole exciton band with increasing electron beam energy we deduce that the impurity and defect densities also increase as a function of depth.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860030142
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    Paper (German National Licenses)
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