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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1666-1668 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous (a-) SiCx:H films were deposited in a rf glow discharge of disilylmethane/silane mixtures. At optical gaps larger than 2 eV these films are found to have a higher photoconductivity than films prepared in conventional CH4/SiH4 gas mixtures. Both types of films are compared with respect to their hydrogen content as well as infrared and effusion spectra.
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 552-558 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hydrogen effusion spectra of oxidized Si samples are investigated and characteristic activation energies associated with the rupture of hydrogen bonds are estimated. Dislocation-enhanced solubility of hydrogen is found in deformed crystals and macroscopic diffusion depth (mm) can be realized. Hydrogenation is performed by exposure of the crystals to H2 gas at 800 °C. Beside the desorption of hydrogen bound close to the Si surface, the rupture of hydrogen-hydrogen bonds of molecules stored in deformed crystals is observed. The storage of the H2 molecules requires the presence of dislocations or deformation-induced point defects, and the H:H binding energy ranges from 2.7 to 3.8 eV. Most likely this energy variation comes from different local strain around dislocations. Atomic hydrogen is found to dominate the effusion kinetics.
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 28 (1987), S. 497-508 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: It is shown that Thomae's identity between two 3F2 hypergeometric series of unit argument together with the trivial invariance under separate permutations of numerator and denominator parameters implies that the symmetric group S5 is an invariance group of this series. A similar result is proved for the terminating Saalschützian 4F3 series, where S6 is shown to be the invariance group of this series (or S5 if one parameter is eliminated by using the Saalschütz condition). Here Bailey's identity is realized as a permutation of appropriately defined parameters. Finally, the set of three-term relations between 3F2 series of unit argument discovered by Thomae [J. Thomae, J. Reine Angew. Math. 87, 26 (1879)] and systematized by Whipple [F. J. Whipple, Proc. London Math. Soc. 23, 104 (1925)] is shown to be transformed into itself under the action of the group S6×Λ, where Λ is a two-element group. The 12 left cosets of S6×Λ with respect to the invariance group S5 are the structural elements underlying the three-term relations. The symbol manipulator macsyma was used to obtain preliminary results.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 1782-1787 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Gas evolution and infrared-absorption studies on a-Si:C:N:H films deposited from hexamethyldisilazane vapor and nitrogen gas by a plasma process show that hydrogen at concentrations of more than 30 at. % is incorporated in the films. The hydrogen evolution spectra are similar to the spectra of a-Si:C:H films deposited from SiH4-CH4 mixtures, suggesting the presence of a continuous void network. At low plasma power a considerable amount of methyl groups is incorporated as detected by infrared absorption, leading to a hydrocarbon effusion in the 500–700 °C region. At high power the effusion of N2 at 600–800 °C indicates the incorporation of molecular nitrogen.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 556-560 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have characterized the structure of superlattices (SL's) based on amorphous silicon by optical interference microscopy and secondary electron micrographs. Differences in the etch rate of a-Si:H and a-SiNx:H in CP6 create a series of terraces and steps in a-Si:H/a-SiNx:H superlattices that show up clearly in interference contrast micrographs and allow an assessment of the quality of the SL. Secondary electron microscopy images of doping superlattices (npnp or nini) of a-Si:H reveal after plasma etching the layered nature of the samples. The necessary contrast is provided by differences in the etch rate of the two interfaces (i.e., n→p vs p→n). Evidence for structural differences of the interfaces of nini multilayers stems from secondary ion mass spectrometry and 15N depth profiles of hydrogen that show an extra amount of H of the order of 1015 cm−2 only at that interface where intrinsic a-Si:H is growing on top of the n-type material. We explain these results in terms of a growth model which entails a hydrogen enrichment over its bulk concentration that is not limited to the surface but extends into a subsurface region during the film deposition.
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 2477-2479 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Temperature-dependent deuterium effusion experiments were performed on deuterated-fluorinated amorphous silicon containing 25% D and 0.5% F. Evolution was made in the dark and under up to AM1 illumination. It was found that illumination enhanced effusion. The effect could be explained by an increased D diffusion, caused by enhanced SiD bond breaking resulting from energy supplied by the decay of photocarriers to midgap states.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of environmental contamination and toxicology 35 (1985), S. 157-162 
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 17 (1988), S. 121-130 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Red-winged blackbirds (Agelaius phoeniceus), brown-headed cowbirds (Molothrus ater), common grackles (Quiscalus quiscula), mallards (Anas platyrhynchos), northern bobwhites (Colinus virginianus), and eastern screech-owls (Otus asio) were poisoned with a concentration of lead (Pb) acetate in the diet which was increased by 60% each week until half of the birds in each treatment group died; surviving birds and all control birds except screech-owis were then killed by euthanasia. An additional group of mallards was poisoned with Pb shot. The gizzards of mallards poisoned either way usually were stained with bile; some of these birds also had proventricular impaction. Most poisoned birds of the other species were emaciated but lacked other gross lesions caused by Pb poisoning. In birds other than mallards, Pb poisoning could not be diagnosed without histological or hematological examinations or analysis of tissues. Poisoned birds of all six species could be reliably separated from control birds by an increase in the protoporphyrin concentrations in the blood and by a decrease in the activity of delta-aminolevulinic acid dehydratase (ALAD) in red blood cells. Hepatic iron (Fe) concentrations varied so much among individual birds that even though median hepatic Fe concentrations increased in poisoned birds, hepatic Fe concentrations were not useful in identifying poisoned birds. Renal intranuclear inclusion bodies occurred in 83% of all birds dying from Pb poisoning. Nephrosis, myocardial necrosis, and arterial fibrinoid necrosis were occasionally present. Median hepatic Pb concentrations varied from 20 ppm (wet wt) in male red-winged blackbirds to 111 ppm in female northern bobwhites. Median renal Pb concentrations varied from 22 ppm in redwinged blackbirds to 190 ppm in female northern bobwhites. Hepatic and renal Pb concentrations varied substantially among birds within each species. Median hepatic and renal Pb concentrations of birds that died were not statistically different (p 〉 0.05) from those of birds that were killed. Lead shot and Pb acetate affected mallards similarly.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Lasers in medical science 4 (1989), S. 159-164 
    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract For photodynamic therapy of tumors in hollow organs a homogeneous distribution of the applied laser light is desirable but often difficult to be achieved. Different irradiation modalities are compared in this paper. A method for homogenization of light using a layer of a highly backscattering medium deposited on the wall of the organ is described. The homogenization effect is studied theoretically for spherical and cylindrical hollow organs and, in part, compared with experimental results. An irradiation efficiency of more than 90% of the applied light dose is expected, i.e. losses can be reduced to 10% only.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Acta applicandae mathematicae 7 (1986), S. 257-311 
    ISSN: 1572-9036
    Keywords: 10 B05 ; 20C35 ; 33A30 ; 81-47 ; 81G30 ; Racah coefficients ; Clebsch-Gordan coefficients ; weight 2 zeros ; Pell equations ; Diophantine equations ; orbit classification of zeros ; symbolic formula manipulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The interface between Racah coefficients and mathematics is reviewed and several unsolved problems pointed out. The specific goal of this investigation is to determine zeros of these coefficients. The general polynomial is given whose set of zeros contains all nontrivial zeros of Racah (6j) coefficients [this polynomial is also given for the Wigner-Clebsch-Gordan (3j) coefficients]. Zeros of weight 1 3j- and 6j-coefficients are known to be related to the solutions of classic Diophantine equations. Here it is shown how solutions of the quadratic Diophantine equation known as Pell's equation are related to weight 2 zeros of 3j- and 6j-coefficients. This relation involves transformations of quadratic forms over the integers, the orbit classification of zeros of Pell's equation, and an algorithm for determining numerically the fundamental solutions of Pell's equation. The symbol manipulation program MACSYMA was used extensively to effect various factorings and transformations and to give a proof.
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