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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 2621-2626 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Based on two different experiments and an optical field calculation, we show that the free-carrier absorption αfc in Zn(Cd)Se/ZnMgSSe semiconductor lasers is about 4 cm−1 and that it is smaller than that of GaAs/AlGaAs semiconductor lasers. We have measured the dependence of the L-I characteristics on the cavity length of double heterostructure (DH) lasers under photopumped operation and of single quantum well-separate confinement heterostructure (SQW-SCH) lasers under current-injected operation. For the DH laser, the total absorption coefficient αi and β×J0 product (β is a gain constant, and J0 is the nominal current density that makes the gain equal to zero) are estimated to be 4.2 cm−1 and 8.6×10 cm−1, respectively. For the SQW-SCH laser, αi, β, and J0 are estimated to be 21 cm−1, 4.23×10−3 cm×μm/A, and 1.9×10−3 A/(cm2×μm), respectively. By calculating the optical fields of these lasers, we have estimated that the absorption in a GaAs substrate is 16.53 cm−1 in the SQW-SCH laser and that it is negligible in the DH laser. We have shown that the large loss in the SQW-SCH laser is caused by both αfc and the absorption in the substrate and that αi in the DH laser is caused only by free carrier absorption.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 4824-4826 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Pressure effects on magnetic transition temperatures of Mn3Ga1−xMxC (M=Zn,Sn) have been measured in order to study the nature of the order-order magnetic phase transitions. The magnetic phase diagrams for the transition temperatures versus concentration and for the transition temperatures versus pressure have been determined. For Mn3Ga1−xZnxC, the intermediate magnetic phase observed in Mn3GaC above 3 kbar appears even at normal atmospheric pressure. On the basis of these results, the relation between the effect of alloying and of pressure on the magnetic transitions of the Mn3Ga1−xMxC (M=Zn,Sn) systems is discussed.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 3181-3185 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The time variation of population densities of V atoms in absorption levels pertinent to an optically pumped atomic V vapor laser is studied experimentally. V vapor is generated from a V metal by irradiation of a pulsed Nd:YAG (λ=1.06 μm) laser of 2 J/pulse energy and 1.4 ms pulse duration. The population densities of the ground-state and excited-state (E∼2400 cm−1) V atoms have been measured by the interferometric method, and the temperature in the vapor is estimated from these populations. It has been experimentally observed that the populations of the ground state and the excited state are about 1×1014/cm3 and 4×1013/cm3, respectively. The temperature in the vapor increased from about 1800 to 4000 K with time during the YAG laser irradiation.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 7253-7256 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Output characteristics of an optically pumped tantalum vapor laser and the distribution of tantalum vapor generated by irradiation of a laser have been investigated experimentally. Ta vapor is generated by irradiation of a pulsed YAG laser and then the Ta atoms are optically pumped by a KrF excimer laser. It is observed that the maximum output energy is 160 nJ, the maximum optical conversion efficiency is 0.01%, and the ground-state Ta atoms are distributed not only in the luminous space of the vapor but also around it.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 4642-4644 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Pressure effects on spin-flop transition temperature (Tsf) of Mn2−xCoxSb have been measured in order to study the nature of spin-flop phase transitions. The magnetic phase diagrams for Tsf versus concentration and for Tsf versus pressure have been determined. Tsf increases with increasing applied pressure (dTsf/dp=2.9 K/kbar for x=0.05, dTsf/dp=3.7 K/kbar for x=0.10, dTsf/dp=3.3 K/kbar for x=0.15, and dTsf/dp=2.7 K/kbar for x=0.20). On the other hand, Tsf decreases slowly with x up to (approximately-equal-to)0.05 and increases rapidly under further increasing x at normal atmospheric pressure. On the basis of these results, the microscopic origin of the magnetic anisotropy of Mn2−xCoxSb is discussed.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 5298-5299 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The pressure effect of the ferromagnetic Curie temperature in Tb(Al1−xCox)2, 0≤x≤0.1 was measured by the induction method under hydrostatic pressure. The Curie temperatures of these compounds increased with increasing pressure and the derivative dTc/dp as a function of cobalt concentration did not change so much compared with that of Gd(Al1−xCox)2 [Sato et al., J. Phys. (Paris) Colloq. 49, C8-453 (1988)]. These results are discussed on the basis of the RKKY model.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 1044-1045 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Laser action has been observed on the vanadium 560.4-, 575.3-, 581.7-, and 637.9-nm lines. Vanadium vapor is produced from a vanadium metal plate by YAG laser (2.0 J/pulse) irradiation, and optically pumped by an XeCl excimer laser of 25-mJ energy. The vanadium laser pulse has a duration of 50 ns and peak output power of about 7 W.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 4816-4817 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Pressure dependence of the magnetic phase transition temperatures of Mn1.8Co0.2Sb were obtained by measuring temperature variation of initial permeability at various pressure. Both the transition temperature (Tt) from antiferromagnetic (AF) to ferrimagnetic (FM) states and the Curie temperature (Tc) increase with increasing pressure. Temperature variations of the lattice parameters of the sample were also measured by using the powder x-ray diffraction method. The discontinuous change of a and c axes and the changes of the thermal expansion coefficients were observed at Tt and Tc, respectively. It is found that the negative exchange striction below Tc and the sign of volume change at Tt are consistent with the results of pressure dependence of Tc and Tt. On the basis of these results, the relation between the effects of alloying and of pressure on the magnetic transitions of Mn2−xCoxSb system is discussed.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 806-806 
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 2564-2570 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Deexcitation cross sections of He(2 1P) by H2 have been measured using a pulse radiolysis method in a region of the mean collisional energy between 18 and 38 meV and compared with those obtained by theoretical calculations. Experimental cross-section values and their collisional energy dependence are interpreted in terms of the Penning ionization cross section based on a long-range dipole–dipole interaction between He(2 1P) and H2. Validity of the theoretical formula for the Penning ionization cross section, i. e., the Watanabe–Katsuura formula, is discussed. The cross section has been further calculated by means of an impact-parameter method with experimentally simulated classical trajectories; a hydrogen molecule has been assumed to be spherical to neglect the rotational effect of H2; it is also assumed that the polarization axis of the p-state helium rotates in order to keep collinear or perpendicular configuration with respect to the axis of He–H2. A modified form of the dipole–dipole autoionization width with an electron exchange interaction is also discussed.
    Materialart: Digitale Medien
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