School of Chemistry - Research Publications

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    2-DIMENSIONAL DIFFUSION OF AMPHIPHILES IN PHOSPHOLIPID MONOLAYERS AT THE AIR-WATER-INTERFACE
    CARUSO, F ; GRIESER, F ; THISTLETHWAITE, PJ ; ALMGREN, M (CELL PRESS, 1993-12-01)
    Steady-state and time-resolved fluorescence spectroscopy has been used to examine lateral diffusion in dipalmitoyl-L-alpha-phosphatidylcholine (DPPC) and dimyristoyl-L-alpha-phosphatidylcholine (DMPC) monolayers at the air-water interface, by studying the fluorescence quenching of a pyrene-labeled phospholipid (pyrene-DPPE) by two amphiphilic quenchers. Steady-state fluorescence measurements revealed pyrene-DPPE to be homogeneously distributed in the DMPC lipid matrix for all measured surface pressures and only in the liquid-expanded (LE) phase of the DPPC monolayer. Time-resolved fluorescence decays for pyrene-DPPE in DMPC and DPPC (LE phase) in the absence of quencher were best described by a single-exponential function, also suggesting a homogeneous distribution of pyrene-DPPE within the monolayer films. Addition of quencher to the monolayer film produced nonexponential decay behavior, which is adequately described by the continuum theory of diffusion-controlled quenching in a two-dimensional environment. Steady-state fluorescence measurements yielded lateral diffusion coefficients significantly larger than those obtained from time-resolved data. The difference in these values was ascribed to the influence of static quenching in the case of the steady-state measurements. The lateral diffusion coefficients obtained in the DMPC monolayers were found to decrease with increasing surface pressure, reflecting a decrease in monolayer fluidity with compression.
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    Two-electron relativistic corrections to the potential energy surface and vibration-rotation levels of water
    Quiney, HM ; Barletta, P ; Tarczay, G ; Csaszar, AG ; Polyansky, OL ; Tennyson, J (ELSEVIER, 2001-08-24)
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    Relativistic density functional theory using Gaussian basis sets
    Quiney, HM ; Belanzoni, P (AMER INST PHYSICS, 2002-09-22)
    A four-component formulation of relativistic density functional theory is presented together with the details of its implemention using a G-spinor basis set. The technical features of this approach are compared to those found in the nonrelativistic density functional theory of quantum chemistry which employ scalar basis sets of Gaussian-type functions. Numerical results of the G-spinor expansion method are presented for a sequence of closed-shell atoms, and for a selection of relativistic density functionals, and are compared with finite difference benchmarks.
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    Anatomy of relativistic energy corrections in light molecular systems
    Tarczay, G ; Csaszar, AG ; Klopper, W ; Quiney, HM (TAYLOR & FRANCIS LTD, 2001-11-01)
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    Cobalt(III) complexes of monobenzyl-cyclam macrocycle derivatives
    Ghiggino, KP ; Grannas, MJ ; Koay, MS ; Mariotti, AWA ; McFadyen, WD ; Tregloan, PA (C S I R O PUBLISHING, 2001-01-01)
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    Refractive-index profiling of optical fibers with axial symmetry by use of quantitative phase microscopy
    Roberts, A ; Ampem-Lassen, E ; Barty, A ; Nugent, KA ; Baxter, GW ; Dragomir, NM ; Huntington, ST (OPTICAL SOC AMER, 2002-12-01)
    The application of quantitative phase microscopy to refractive-index profiling of optical fibers is demonstrated. Phase images of axially symmetric optical fibers immersed in index-matching fluid are obtained, and the inverse Abel transform is used to obtain the radial refractive-index profile. This technique is straightforward, nondestructive, repeatable, and accurate. Excellent agreement, to within approximately 0.0005, between this method and the index profile obtained with a commercial profiler is obtained.