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  • 1
    Electronic Resource
    Electronic Resource
    Analysis of liquid surface films by pulsed laser photoacoustic spectroscopy (1987)
    Springer
    Applied physics 43 (1987), S. 1-7 
    Details
    ISSN: 1432-0649
    Keywords: 68.15.+e ; 78.65.−s ; 78.20.Nv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The photoacoustic generation of plane acoustic waves in strongly absorbing or opaque liquids by pulsed laser radiation is discussed both experimentally and theoretically. The regimes of a confined and a free surface of the liquid are considered. The model which takes the temporal shape of the laser pulses applied in the experiments into account, implies that spectroscopic studies are feasible with direct photoacoustic generation and detection also for opaque liquids. The experiments are performed with a tunable hybrid CO2 laser and piezoelectric detection. For the first time liquid/liquid interfaces are studied by this technique. We demonstrate that the presence of an absorbing liquid film with a thickness of 〉1 μm on the surface of another liquid amplifies the acoustic signal which is detected in the bottom liquid. The enhancement depends on the thickness and the optical and thermal properties of the film medium. The surface layer can be analyzed on the basis of the photoacoustic spectrum. It is also shown that this non-contact method is surface-film selective and should thus prove useful for pollution analysis of liquid surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00693965
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  • 2
    Electronic Resource
    Electronic Resource
    The role of rotational tunneling in the metastable decay of rare gas cluster ions (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 6335-6340 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The decay of (Ar+3)*→Ar+2+Ar is found to be metastable on a time scale longer than 40 μs. Theoretical considerations are presented for these slow metastable dissociation rates reported in this and other studies. From model calculations it is inferred that tunneling lifetimes from 10−10 to 10 s may be observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454471
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  • 3
    Electronic Resource
    Electronic Resource
    A scaled fundamental equation for the thermodynamic properties of carbon dioxide in the critical region (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 1717-1725 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A scaled fundamental equation is presented for the thermodynamic properties of carbon dioxide in the critical region. The equation is constructed by combining earlier experimental pressure data of Michels and co-workers with new specific heat data obtained by one of the authors and represents the thermodynamic properties of carbon dioxide in the critical region at temperatures from 301.15 to 323 K and at densities from 290 to 595 kg/m3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453238
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  • 4
    Electronic Resource
    Electronic Resource
    Studies of mass diffusion of camphorquinone in linear and crosslinked polystyrene by the laser induced holographic relaxation technique (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 5359-5364 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Laser induced holographic grating relaxation studies of camphorquinone (CQ) diffusing in liner polystyrene (PS) (with both narrow and wide molecular weight distribution) and crosslinked PS (with bis-phenol-A-dimethacrylate as the crosslinking agent) are carried out. Diffusion coefficients of CQ in the polymer hosts are obtained from the decay rate of the intensity diffracted from the laser induced holographic grating. The diffusion coefficients (D) of CQ in polydispersed PS samples are compared with that in nearly monodispersed sample. Diffusion coefficients are found to be equal in both types of polymer samples over the whole temperature range studied, thereby indicating that at high molecular weight the molecular weight distribution has little effect on the diffusion coefficient of CQ. The diffusion coefficient of CQ in crosslinked PS is found to decrease with increasing concentration of the crosslinking agent. It decreases approximately 30 times as the concentration of the crosslinking agent increases to 20%. The relationship between the concentration of the crosslinking agent and polymer free volume is discussed. The diffusion coefficients of CQ in linear and crosslinked PS are also measured as a function of temperature. It is found that the temperature dependence of both D and D/T can be described by a Williams–Landel–Ferry (WLF) equation. However, the WLF constants C1 and C2 differ in both fits. The C2 constant obtained from the D/T vs T fit for linear PS sample agrees with that extracted from the viscoelastic measurement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451822
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  • 5
    Electronic Resource
    Electronic Resource
    Ar+3 photodissociation and its mechanisms (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 4019-4025 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photodissociation spectrum of Ar+3 between 520 and 620 nm is reported. A broadband peaking near 520 nm is observed with a cross section of ∼1.8×10−16 cm2 at the peak, in agreement with the findings of Levinger et al. [J. Chem. Phys. 89, 71 (1988)]. However, in the present work, a shoulder whose prominence is highly temperature dependent is observed between 545 and 555 nm. The new results are discussed in terms of various electronic transitions and pathways to dissociation. The photodissociation mechanisms are studied by translational energy analysis of photofragmentation. Three photodissociation mechanisms that involve two electronic energy surfaces are proposed which account for the experimental findings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456832
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  • 6
    Electronic Resource
    Electronic Resource
    Direct and indirect immunofluorescent findings in dermatomyositis (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cutaneous pathology 12 (1985), S. 0 
    Details
    ISSN: 1600-0560
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Three skin biopsies (proximal nailfold, extensor forearm and buttock) and serum samples were studied by direct and indirect immunofluorescence, immunodiffusion and radioimmunoassay techniques in 6 patients with dermatomyositis. A variety of seroligic and immunopathologic abnormalities was observed in the patients. Three of ft patients had antinuclear antibodies (ANA) of a speckled pattern mixed with a peculiar dot pattern. Epidermal intercellular deposits of immunoglobulins were seen in the nailfold biopsies of 2 patients; one of them also had IgG deposits in the cytoplasm of epidermal cells. Forearm and buttock biopsies were negative.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0560.1985.tb00425.x
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  • 7
    Electronic Resource
    Electronic Resource
    Optical and electrical characterization of high-resistivity liquid-phase-epitaxial In0.53Ga0.47AsB: Fe (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 4574-4579 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Semi-insulating In0.53Ga0.47As with carrier concentration n=1.2×1012 cm−3, resistivity up to 1090 Ω cm, and mobility up to 9500 cm2/V s at 300 K is grown by liquid-phase epitaxy and doping with Fe. The influence of Fe doping on the photoluminescence of In0.53Ga0.47As is systematically investigated. An acceptor level at Ev+150 meV, tentatively assigned to Fe by some of us earlier, is definitively identified as an Fe-related complex. This acceptor level, however, is not responsible for the semi-insulating behavior of In0.53Ga0.47As as shown by statistical calculations. High-resolution deep-level transient spectroscopy experiments show two deep acceptors at EC−ET=0.44 and 0.30 eV, respectively. The first one, which dominates, is identified as being caused by the Fe3+/Fe2+ acceptor level. The second, somewhat weaker one, might be caused by the O-related trap recently discovered by Loualiche et al. [Appl. Phys. Lett. 51, 1361 (1987).] Combining the Fe acceptor energy position in In0.53Ga0.47As with its known value in InP and the known conduction-band discontinuity of the InP/In0.53Ga0.47As heterointerface we find that the vacuum referred binding energy model is approximately but not strictly valid. In this model the transition-metal impurity levels are aligned with respect to the vacuum level across interfaces regardless of the surrounding host crystal environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341260
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  • 8
    Electronic Resource
    Electronic Resource
    Doping effects of 3D metal on single-phase YBa2Cu3O7−δ (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 3589-3592 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The measurements of x-ray diffraction, the temperature dependence of the dc resistance and the ac susceptibility have been performed for the single-phase 3D-metal doping systems YBa2 Cu3−x Mx Oy (M=Fe, Co, and Ni; x=0.025, 0.05, 0.075, 0.10, 0.25, and 0.50 for Ni and Co and 0.05, 0.075, 0.10, 0.15, and 0.20 for Fe). With an increase of impurity content, two structural transitions were observed for the Co and Fe dopants but only one for the Ni dopant. The resistivity in the normal state changes from metallic to semiconductinglike behavior and the depression of Tc is linear with the impurity concentration (x) when x〈0.10. A weak Curie–Weiss type paramagnetism, which is enhanced with impurity content, exists in the samples studied. Incorporating other work on oxygen defects, we suggest that a change of oxygen content induced by doping was the dominant effect on superconductivity in these samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341393
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of spin-orbit interaction on heterojunction band discontinuities (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 2970-2972 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of spin-orbit interaction is included in the linear combination of atomic orbitals calculation of heterojunction band discontinuities. It is found that spin-orbit interaction is not negligible when the atomic number of the constituent atoms exceeds about 40. The effect of spin-orbit interaction as well as some interesting observations and their implications are briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335242
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  • 10
    Electronic Resource
    Electronic Resource
    First observation of a titanium midgap donor level in In0.53Ga0.47As p-n diodes (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 645-647 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Growth of Ti-doped In0.53Ga0.47As using liquid phase epitaxy is reported. The energy position of the Ti4+/Ti3+ deep donor level in In0.53Ga0.47As p-n diodes is precisely identified for the first time by deep level transient spectroscopy. The near midgap location of this level at EC−ET =0.37 eV and the potential of InGaAs:Ti of superior thermal stability make it a promising dopant for growing semi-insulating In0.53Ga0.47As. A recent model suggesting the energy positions of transition metals not to vary across heterojunctions is tested and found to be at least qualitatively valid for this low spin transition metal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101810
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