ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Experimental deuteron magnetic resonance study of orientational order in the nematic phase of a binary mixture of biaxial molecules (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 3885-3895 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Deuteron magnetic resonance (2H-NMR) spectra have been obtained from a binary mixture of 2-fluorenyl-4'-tetradecyloxy benzoate-d9 (FLOC14) and para-xylene-d10 (p-xy) as a function of temperature [Hoatson et al. Mol. Cryst. Liq. Cryst. (to be published)]. The liquid crystal FLOC14 is selectively deuterated on the rigid fluorene moiety, while p-xy is perdeuterated. Nonlinear least-squares fits to the quadrupolar splittings νkQ allow unambiguous determination of the temperature dependence of the orientational order parameters Sizz and (Sixx−Siyy) of both species i=1,2. These results are the first to provide information on the degree and asymmetry of orientational order of both biaxial molecules in the uniaxial nematic phase of a binary mixture. The new approach introduced to analyze the experimental data allows for an arbitary orientation of the rigid core relative to the molecular axis. The results demonstrate that the splittings and derived order parameters are insensitive to this twist angle. The experimental results are interpreted using a new mean field theory of binary mixtures of biaxial molecules [Palffy-Muhoray and Hoatson (to be published)]. There is good agreement between the predictions of theory and the component order parameters determined from 2H-NMR experiments, over the entire temperature range studied. Thus this description is capable of predicting the temperature dependence and interrelation of the nematic orientational order parameters for both biaxial molecules in a binary mixture. The derived theoretical parameters are interpreted as the ratios of intermolecular interaction strengths.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460664
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The gravitational field of plane symmetric thick domain walls (1990)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 31 (1990), S. 2683-2687 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: Exact solutions of Einstein's equations for a scalar field with a potential V(Φ) =V0 cos2(1−n) (Φ/f(n)) (0〈n〈1) are presented describing the gravitational field of thick, plane symmetric domain walls. The scalar field has a time-independent kinklike distribution, whereas the metric depends on a time coordinate. The metric is conformally flat and the hypersurfaces parallel to the wall (z=const) are three-dimensional de-Sitter spaces. A particle horizon exists on which the metric becomes Minkowski space. It is shown that the gravitational field experienced by a test particle is repulsive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.528969
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Mechanistic aspects of fullerene coalescence upon ultraviolet laser desorption from thin films (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 262-270 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Positively and negatively charged coalescence products of C60 and C70 were characterized following pulsed laser desorption from fullerene thin films. Coalescence occurs by gas-phase reactions. Positive ions are generated by thermoionization of hot neutrals, while negative ions likely form by electron attachment to neutral species in the outermost region of the desorption plume. Thermoionization rate and surface-induced dissociation (SID) measurements are consistent with fullerene-like structures for coalescence products detected as positive ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466995
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Formation of C119 by thermal decomposition of C60O (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 540-543 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Laser desorption mass spectra of thin films of pure C60O were recorded in a range of equilibrium sample temperatures from 300 to 1100 K. On heating of the sample above 650 K a new peak corresponding to C−119 is detected in the anion mass spectrum which persists even after the sample is cooled to 300 K. Possible solid state reactions leading to the formation of C119 are discussed based on the mass spectrometric observations as well as temperature programmed decomposition measurements which were carried out for C60 and C60O samples. The results are discussed in connection with recently reported polymerization reactions of fullerene materials. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469432
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Enhanced coalescence upon laser desorption of fullerene oxides (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 3243-3249 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: C60Ox, x=1–3 were prepared by exposing C60 solutions to ozone. After high performance liquid chromatography purification, these materials were studied by laser desorption time of flight mass spectroscopy. These mass spectra suggest that fullerene oxides undergo laser desorption induced coalescence more efficiently than pure C60. A correlation between the fragmentation of the desorbed parent species and the observed coalescence products both in yield and distribution suggests that efficient gas phase coalescence involves at least one reactive species, such as C58, produced by fragmentation of the desorbed fullerenes or fullerene derivatives.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467571
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Properties of size and composition selected gas phase alkali fulleride clusters (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 5684-5695 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Neutral and positively charged clusters Mx(C60)z, where M=K/Rb and z=1–3 were prepared in pulsed molecular beams by laser desorption (266 nm) from preformed alkali metal fulleride thin films. Experimental results encompassed mass spectral characterization of beam abundance and in selected cases, determination of rough ionization potential brackets and elucidation of fragmentation pathways upon (i) unimolecular dissociation in gas phase and (ii) surface collision induced dissociation from Si(111). Results are contrasted with electrostatic model calculations as well as ab initio self-consistent field computations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467134
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Impurity toroidal rotation and transport in Alcator C-Mod ohmic high confinement mode plasmas : The 41st annual meeting of the division of plasma physics of the american physical society (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 1825-1830 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Central toroidal rotation and impurity transport coefficients have been determined in Alcator C-Mod [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)] Ohmic high confinement mode (H-mode) plasmas from observations of x-ray emission following impurity injection. Rotation velocities up to 3×104 m/sec in the co-current direction have been observed in the center of the best Ohmic H-mode plasmas. Purely ohmic H-mode plasmas display many characteristics similar to ion cyclotron range of frequencies (ICRF) heated H-mode plasmas, including the scaling of the rotation velocity with plasma parameters and the formation of edge pedestals in the electron density and temperature profiles. Very long impurity confinement times (∼1 sec) are seen in edge localized mode-free (ELM-free) Ohmic H-modes and the inward impurity convection velocity profile has been determined to be close to the calculated neoclassical profile. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.874004
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Mode conversion electron heating in Alcator C-Mod: Theory and experiment : The 41st annual meeting of the division of plasma physics of the american physical society (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 1886-1893 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Localized electron heating [full width at half maximum of Δ(r/a)(approximate)0.2] by mode converted ion Bernstein waves (IBW) has been observed in the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]. These experiments were performed in D(3He) plasmas at high magnetic field (B0=7.9 T), high-plasma density (ne0≥1.5×1020 m−3), and for 0.05≤nHe-3/ne≤0.30. Electron heating profiles of the mode converted IBW were measured using a break in slope analysis of the electron temperature versus time in the presence of rf (radio frequency) modulation. The peak position of electron heating was found to be well-correlated with 3He concentration, in agreement with the predictions of cold plasma theory. Recently, a toroidal full-wave ion cyclotron range of frequencies (ICRF) code TORIC [M. Brambilla, Nucl. Fusion 38, 1805 (1998)] was modified to include the effects of IBW electron Landau damping at (k⊥ρi)2(very-much-greater-than)1, This model was used in combination with a 1D (one-dimensional) integral wave equation code METS [D. N. Smithe et al., Radio Frequency Power in Plasmas, AIP Conf. Proc. 403 (1997), p. 367] to analyze these experiments. Model predictions were found to be in qualitative and in some instances quantitative agreement with experimental measurements. A model for mode conversion current drive (MCCD) has also been developed which combines a toroidal full wave code with an adjoint evaluation of the ICRF current drive efficiency. Predictions for off-axis MCCD in C-Mod have been made using this model and will be described. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.874012
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    The effect of divertor baffling on Alcator C-Mod discharges : The 41st annual meeting of the division of plasma physics of the american physical society (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 1894-1903 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of divertor baffling on Alcator C-Mod [Hutchinson et al., Phys. Plasmas 1, 1511 (1994)] discharges has been investigated using a novel divertor bypass. The bypass allows the in situ variation of the mechanical conductance from the divertor plenum to the main chamber between or even during discharges. The results indicate a strong dependence on baffling for the compression of deuterium and recycling impurity gases in the divertor plenum in a variety of C-Mod discharges, indicating that tight baffling would be desirable in a future tokamak reactor. There is no apparent effect of the divertor baffling for the Ohmic, L-mode and EDA (Enhanced Dα) H-mode discharges in this study on main chamber neutral particle populations, scrape-off-layer flows, nonrecycling impurity screening, global energy confinement or H-mode threshold powers. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.874013
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Effects of neutral particles on edge dynamics in Alcator C-Mod plasmas : The 41st annual meeting of the division of plasma physics of the american physical society (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 1919-1926 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Neutral particle densities and energy losses have been measured in the Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]. Their effect on the formation and evolution of the edge barrier which accompanies the enhanced confinement regime are discussed. The neutrals can enter the edge dynamics through the particle, momentum, and energy balance. Neutral densities of up to 5×1016 m−3 have been measured in the edge barrier region. Neutrals enter the local dynamics around most of the periphery, not just at the X-point. High resolution measurements of the ionization profile have been obtained for the region near the separatrix. The profile shifts inside the separatrix as the plasma is making a transition from low-to high-mode confinement (H-mode) regimes, partly accounting for the dramatic rise in edge density. The measured neutral density is large enough to affect the bulk ion momentum by charge exchange, and thereby introduces a negative radial electric field at the edge. At the same time, significant edge heat flux, carried by the neutrals, contributes to the measured power loss. At very high edge densities, this loss mechanism could contribute to quenching H-modes. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.874016
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...