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  • 1
    Digitale Medien
    Digitale Medien
    Photodissociation of hydrogen sulfide at 157.6 nm: Observation of SH bimodal rotational distribution (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 3940-3945 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Photodissociation of the H2S molecule at 157.6 nm was studied experimentally using the Rydberg tagging technique. Translational energy distributions of the H-atom product from the H2S photodissociation were measured, and the SH(X 2Π)+H(2S) channel was found to be the dominant dissociation process. Spin-orbit and rovibrational state distributions were also obtained for the SH product, which was found to be both vibrationally and rotationally excited. An intriguing bimodal rotational distribution in the lowest two vibrational states, v=0 and 1, has been clearly observed for the SH product, indicating that there are two distinctive dissociation mechanisms involved in the photodissociation of H2S at 157 nm excitation. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.479736
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  • 2
    Digitale Medien
    Digitale Medien
    Ba-REE fluorcarbonate minerals froma carbonatite dyke at Bayan Obo,Inner Mongolia, North China (2000)
    Springer
    Mineralogy and petrology 70 (2000), S. 221-234 
    Details
    ISSN: 1438-1168
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Ba-SEE Fluorkarbonate Cebait, Huangoit und Cordylit kommen in einem Karbonatitgang bei Bayan Obo, Innere Mongolei, Nord-China, vor. Ihre chemische Zusammensetzung, SEE-Verteilungsmuster und syntaktische Verwachsungsbeziehungen werden vorgestellt. Letztere wurden mit Mikrosonden-Rastermethoden untersucht und im Zusammenhang mit der Abkühlungsgeschichte des Karbonatit-Magmas oder eventueller späterer Ereignisse interpretiert. Die SEE-Verteilungsmuster der Ba-SEE Fluorkarbonate im Gang ähneln denen entsprechender Minerale im Dolomit-Marmor in dem die Großlagerstätte Bayan Obo aufsitzt; dies weist darauf hin, dass beide kogenetisch sein koönnten.
    Notizen: Summary The new occurrence in a carbonatite dyke at Bayan Obo, Inner Mongolia, North China, of the Ba-REE fluorocarbonate minerals cebaite, hunghoite and cordylite is presented, together with their chemical composition, rare earth element (REE) patterns, and syntaxial intergrowth relationships. These syntaxial textures, investigated by scanning and electron microprobe techniques, are interpreted in terms of the cooling history during the late-stage crystallization of the carbonatite magma or possible later events. The REE distribution patterns of the Ba-REE fluorocarbonate minerals in the dyke are similar to those of the corresponding minerals in the dolomite marble that hosts the giant REE-Nb-Fe ore body at Bayan Obo, providing evidence that the two may be cogenetic.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s007100070004
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  • 3
    Digitale Medien
    Digitale Medien
    Theorems of the Alternative and Optimization with Set-Valued Maps (2000)
    Springer
    Journal of optimization theory and applications 107 (2000), S. 627-640 
    Details
    ISSN: 1573-2878
    Schlagwort(e): vector optimization ; set-valued maps ; generalized convexity ; equivalent conditions ; theorem of the alternatives ; optimality conditions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract In this paper, the concept of generalized cone subconvexlike set-valued mapsis presented and a theorem of alternative for the system of generalizedinequality–equality set-valued maps is established. By applying thetheorem of the alternative and other results, necessary and sufficientoptimality conditions for vector optimization problems with generalizedcone subconvexlike set-valued maps are obtained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1026407517917
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  • 4
    Digitale Medien
    Digitale Medien
    Intracerebroventricular Administration of AT1 Receptor Antisense Oligonucleotides Inhibits the Behavioral Actions of Angiotensin II (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 62 (1994), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: Antisense Oligonucleotides were developed to study the expression and function of angiotensin type 1 (AT1) receptors in cultured cells and brain. In both liver epithelial WB and neuro-blastoma N1E-115 cells AT1 antisense oligomers substantially decreased AT1 receptor density, whereas angiotensin type 2 (AT2) receptors remained unchanged. Similarly, repeated intracerebroventricular injections of AT1 antisense oligomers in rats decreased AT1 receptor density in hypothalamic-thalamic-septal tissue, and AT2 receptors were unaffected. Intracerebroventricular antisense oligomers also attenuated drinking elicited by intra-cerebroventricular angiotensin II but not the cholinomimetic carbachol. Collectively, these results demonstrate that antisense Oligonucleotides attenuate angiotensin receptor expression and function in behaving animals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1471-4159.1994.62052053.x
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  • 5
    Digitale Medien
    Digitale Medien
    Toward the understanding of ethylene photodissociation: Theoretical study of energy partition in products and rate constants (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 10810-10820 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The energy partition in the products of ethylene photodissociation (including C2H4, C2D4, D2CCH2, cis- and trans-HDCCDH) at 193 and 157 nm and the rate constants of H loss channels were computed based on ab initio ethylene ground-state surfaces of which most were reported earlier. In the calculations of the energy partitions, a simple model was used in which the excess energy above the transition state is distributed statistically and the energy released by the exit barrier is described by the modified impulsive model. The rate constants of the ethylene H(D) elimination were calculated according to the variational RRKM (Rice–Ramsperger–Kassel–Marcus) theory, and the RRKM rate constants with tunneling corrections were obtained for vinyl decomposition at 193 nm. In contrast with previous conclusions drawn by LIF (laser induced fluorescence) studies, the rate constant calculations suggest that the H loss may be a nonstatistical process. However, the computed variational transition states for H loss appear reasonable as indicated by the translational energy. That with present investigation indicates that the atomic elimination proceeds via the predicted transition states though the process is nonstatistical. Analysis of the H2 translational energy measured at 193 and 157 nm by molecular beam experiments gives evidence that the overall mechanisms of the molecular elimination are different at the two wavelengths, which is also in disagreement with previous belief. At 193 nm, both H2 elimination channels may occur through the predicted transition states. On the other hand, further comparison of the theoretical and experimental translational energy of hydrogen molecule at 157 nm suggests that the observed (1,1E) reaction path is most likely of much higher "exit barrier" than the one computed. For the (1,2E) channel, the calculations are still in support of the computed transition state being the one along the experimentally observed pathway at 157 nm. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.478999
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  • 6
    Digitale Medien
    Digitale Medien
    Photodissociation of NO2 at 355 and 351 nm Investigated by Photofragment Translational Spectroscopy (1994)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 98 (1994), S. 12260-12269 
    Details
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/j100098a023
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  • 7
    Digitale Medien
    Digitale Medien
    Optical study of heterointerface configuration in narrow GaAs/AlGaAs single quantum wells prepared with growth interruption (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 1073-1077 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Photoluminescence and time-resolved photoluminescence were used to study the heterointerface configuration in GaAs/AlGaAs quantum wells grown by molecular-beam epitaxy with growth interruption. Photoluminescence spectra of the growth-interrupted sample are characterized by multiplet structures, with energy separation corresponding to a 0.8 monolayer difference in well width, rather than 1 monolayer as expected from the "atomically smooth island'' picture. By analyzing the thermal transfer process of the photogenerated carriers and luminescence decay process, we further exploit the exciton localization at the interface microroughness superimposed on the extended growth islands. The lateral size of the microroughness in our sample was estimated to be 5 nm, less than the exciton diameter of 15 nm. Our results strongly support the bimodal roughness model proposed by Warwick et al. [Appl. Phys. Lett. 56, 2666 (1990)]. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.360896
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  • 8
    Digitale Medien
    Digitale Medien
    Imaging nanometer-thick patterned self-assembled monolayers via second-harmonic generation microscopy (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 2051-2054 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have used the inherent surface sensitivity of second-harmonic generation to develop an instrument for nonlinear optical microscopy of surfaces and interfaces. This optical technique is ideal for imaging nanometer-thick, chromophoric self-assembled monolayers (SAMs), which have been patterned using photolithographic techniques. In this paper, we demonstrate the application of second-harmonic generation microscopy to patterned SAMs of the noncentrosymmetric molecule calixarene and discuss the resolution and sensitivity limits of the technique. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.364284
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  • 9
    Digitale Medien
    Digitale Medien
    Optical properties of wurtzite GaN grown by low-pressure metalorganic chemical-vapor deposition (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 3691-3696 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We present the results of optical studies on the properties of GaN grown by low-pressure metalorganic chemical-vapor deposition, with emphasis on the issues vital to device applications such as stimulated emission and laser action as well as carrier relaxation dynamics. By optical pumping, stimulated emission and lasing were investigated over a wide temperature range up to 420 K. Using a picosecond streak camera, the free and bound exciton emission decay times were examined. In addition, the effects of temperature and pressure on the optical interband transitions and the transitions associated with impurity/defect states were studied using a variety of spectroscopic methods, including photoluminescence and photoreflectance. The fundamental band gap of GaN was mapped out as a function of temperature using the empirical Varshni relation. The pressure coefficient of the gap was determined using diamond-anvil pressure-cell technique. The hydrostatic deformation potential for the direct Γ band gap was also derived from the experimental results. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.361200
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  • 10
    Digitale Medien
    Digitale Medien
    Dissociation dynamics of the water molecule on the A˜ 1B1 electronic surface (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 10597-10604 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Photodissociation of H2O, D2O, and HOD on the A˜ 1B1′ surface through 157.6 nm excitation has been studied using the H(D) atom Rydberg tagging time-of-flight technique. Vibrational state distribution has been measured for the OH/OD product from the photodissociation of the H2O, D2O, and HOD molecules. Comparisons of our results with previous theoretical calculations and experimental results obtained using the laser induced fluorescence (LIF) technique have been made. Experimental results in this work indicate that the relative populations for vibrationally excited OH(v≥2) products measured using LIF are significantly underestimated, suggesting that LIF as a technique to quantitatively measure vibrational distributions of reaction product OH is seriously flawed. The experimental results presented here are in rather good agreement with previous theoretical calculations. However, our results indicate that the calculated vibrational populations for the higher vibrational states of OH are still somewhat overestimated. Relative branching ratio of H and D productions from HOD has also been estimated. This complete set of data for the photodissociation of H2O should provide an excellent testing ground for improving the theoretical potential energy surface of the first electronically excited state of the water molecule. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1285899
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