Room-temperature phosphorescence and fluorescence of nitrogen heterocyclics adsorbed on silica gel chromatoplates

The room-temperature phosphorescence of benzof]quinoline and phenanthridine has been enhanced considerably by spotting HBr-ethanol solutions of the compounds onto silica gel chromatoplates. Acridine showed no room-temperature phosphorescence but gave very strong fluorescence on silica gel chromatoplates. The analytical aspects are discussed, and some evidence is provided for the interactions of the compounds with the substrate.     

Analytical and mechanistic aspects of the room-temperature fluorescence and phosphorescence of benzo(f)quinoline adsorbed on silica gel chromatoplates with humidified gases

The solid-matrix room-temperature fluorescence and room-temperature phosphorescence properties of benzo(f)quinoline adsorbed on silica gel chromatoplates were investigated over a wide range of humidities in N(2), air and O(2). Both neutral and acidic conditions were used and even at the highest relative humidity used, 93% relative humidity, the room-temperature fluorescence and phosphorescence intensities from benzo(f)quinoline were not totally quenched. However, in all experiments, the room-temperature phosphorescence was much more sensitive to humidity quenching than the room-temperature fluorescence. The results gave rather detailed information on quenching of the room-temperature fluorescence and phosphorescence in the different gases at a variety of humidities. It was possible to calculate the contribution to the percent decrease in luminescence due to moisture or a quenching gas. Thus, a more detailed assessment could be made about the quenching of moisture and individual quenching gases on the solid-matrix fluorescence and phosphorescence.     

The effects of adsorption of solutes on glassware and teflon in the calculation of partition coefficients for solid-phase microextraction with 1PS paper

Solid-phase microextraction presents numerous advantages over traditional extraction techniques. However, the determination of partition coefficients is not as simple as it may appear. For very nonpolar compounds, such as polycyclic aromatic compounds, adsorption to the glass wall of the extraction vial and the Teflon coating of the stir bar may be quite significant. These interactions must be taken into account when calculating partition coefficients. Failing to do this may lead to large errors in the value of the partition coefficient, particularly for very nonpolar compounds. Three polar compounds and seven polycyclic aromatic hydrocarbons were partitioned individually between Whatman 1PS paper and water solutions of the compounds. The partition coefficiencts were calculated with two equations, and detailed mass balance data were acquired for the adsorption of the solute on the stir bar, glass vial, and 1PS paper. The mass data were compared with the partition coefficients, and important conclusions were made about the practical use of the partition coefficients.     

Surfaces and the Sklyanin Bracket

 We discuss the Lie Poisson group structures associated to splittings of the loop group LGL(N,ℂ), due to Sklyanin. Concentrating on the finite dimensional leaves of the associated Poisson structure, we show that the geometry of the leaves is intimately related to a complex algebraic ruled surface with a ℂ ^*-invariant Poisson structure. In particular, Sklyanin's Lie Poisson structure admits a suitable abelianisation, once one passes to an appropriate spectral curve. The Sklyanin structure is then equivalent to one considered by Mukai, Tyurin and Bottacin on a moduli space of sheaves on the Poisson surface. The abelianization procedure gives rise to natural Darboux coordinates for these leaves, as well as separation of variables for the integrable Hamiltonian systems associated to invariant functions on the group. Received: 8 August 2001/Accepted: 29 April 2002 Published online: 14 October 2002 RID="★" ID="★" The first author of this article would like to thank NSERC and FCAR for their support RID="★★" ID="★★" The second author was partially supported by NSF grant number DMS-9802532     

Photoinduced hyper-reflective cholesteric liquid crystals enabled via surface initiated photopolymerization

A structured polymer was synthesized by surface initiated photopolymerization in the presence of a cholesteric liquid crystal (CLC). The templated helical polymer (traversing 2/3 the cell thickness) was backfilled with an opposite handedness, photoresponsive CLC mixture yielding a photo-induced, large contrast, hyper-reflective (R > 99%) CLC film.     

SU(2) monopoles of charge 2

Using the methods of Hitchin, the moduli space of SU(2) monopoles of charge two is computed.     

On the geometry of isomonodromic deformations

This note examines the geometry behind the Hamiltonian structure of isomonodromy deformations of connections on vector bundles over Riemann surfaces. The main point is that one should think of an open set of the moduli of pairs (V,∇)$(V,\nabla )$ of vector bundles and connections as being obtained by “twists” supported over points of a fixed vector bundle _V0$V_0$ with a fixed connection _∇0${\nabla }_0$; this gives two deformations, one, isomonodromic, of (V,∇)$(V,\nabla )$, and another induced from the isomonodromic deformation of (_V0,_∇0)$(V_0,{\nabla }_0)$. The difference between the two will be Hamiltonian.     

Separating Coordinates for the Generalized Hitchin Systems and the Classical r-Matrices

We exhibit natural Darboux coordinates for the generalized Hitchin systems studied by Bottacin and Markman. These systems are defined on spaces of stable pairs consisting of a vector bundle and a form-valued meromorphic endomorphism of the bundle. In special cases (genus zero, genus one), the bundles are rigid and one has the rational, trigonometric and elliptic Gaudin systems. Explicit formulae are given in these cases.