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  • 1995-1999  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Contributions to mineralogy and petrology 136 (1999), S. 213-224 
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The water solubility in haplogranitic melts (normative composition Ab39Or32Qz29) coexisting with H2O-H2 fluids at 800 and 950 °C and 1, 2 and 3 kbar vapour pressure has been determined using IR spectroscopy. The experiments were performed in internally heated pressure vessels and the hydrogen fugacity (f H2) was controlled using the double capsule technique and oxygen buffer assemblages (WM and IW). Due to the limited lifetimes of these oxygen buffers the water solubility was determined from diffusion profiles (concentration-distance profiles) measured with IR spectroscopy in the quenched glasses. The reliability of the experimental strategy was demonstrated by comparing the results of short- and long-duration experiments performed with pure H2O fluids. The water solubility in Ab39Or32Qz29 melts equilibrated with H2O-H2 fluids decreases progressively with decreasing f H2O, as f H2 (or X H2) increases in the fluid phase. The effect of H2 on the evolution of the water solubility is similar to that of CO2 or another volatile with a low solubility in the melt and can be calculated in a first approximation with the Burnham water solubility model. Recalculation of high temperature water speciation for AOQ melts coexisting with H2O-H2 fluids at 800 °C, 2 kbar suggests that the concentrations of molecular H2O are proportional to f H2O (calculated using available mixing models), indicating Henrian behaviour for the solubility of molecular H2O in haplogranitic melts.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2014-02-26
    Description: The method of symmetry adapted wavepackets (SAWP) to solve the time-dependent Schrödinger equation for a highly symmetric potential energy surface is introduced. The angular dependence of a quantum-mechanical wavepackets is expanded in spherical harmonics where the number of close-coupled equations for the corresponding radial functions can be efficiently reduced by symmetry adaption of the rotational basis using the SWAP approach. Various techniques to generate symmetry adapted spherical harmonics (SASHs) for the point groups of highest symmetry (octahedral, icosahedral) are discussed. The standard projection operator technique involves the use of Wigner rotation matrices. Two methods to circumvent numerical instabilities occuring for large azimuthal quantum numbers are suggested. The first is based on a numerical scheme which employs Gaussian integrations yielding exact and stable results. The second is a recursive algorithm to generate higher order SASHs accurately and efficiently from lower order ones. The paper gives a complete set of ``seed functions'' generated by projection techniques which can be used obtain SASHs for all irreducible representations of the octahedral and icosahedral point groups recursively.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
    Format: application/postscript
    Format: application/pdf
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  • 3
    Publication Date: 2014-02-26
    Description: The photoassociation process shows strong dependence on the temporal duration of the electromagnetic field pulses and their frequencies. This dependence is investigated using quantum mechanical simulations that include all ranges of impact parameters and contributions from bound-to-bound transitions. The photoassociation yield of mercury atoms to produce excimer dimers is enhanced for short (ps) and for ultrashort (fs) pulse durations. Ultrashort laser pulses effectively overlap the entire range of free-to-bound transition, therefore achieving a maximum probability. Short pulses show a maximum in the photoassociation yield when their carrier frequency overlaps a particular free-to-bound spectroscopic resonance. Implications of these calculations on efforts to control bimolecular reactions are discussed.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
    Format: application/postscript
    Format: application/pdf
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  • 4
    Publication Date: 2023-08-14
    Language: English
    Type: article , doc-type:article
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