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Your search keyword '"Gennip, van, W.J.H"' showing total 9 results
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9 results on '"Gennip, van, W.J.H"'

1. Toward measuring concentration gradients in polymer-dispersed liquid crystals with secondary ion mass spectrometry

Author

Kjellander, B.K.C., IJzendoorn, van, L.J., Jong, de, A.M., Broer, D.J., Gennip, van, W.J.H., Voigt, de, M.J.A., Niemantsverdriet, J.W., Chien, L.-C., Wu, M.H., and Inorganic Materials & Catalysis

Subjects
chemistry.chemical_classification, Vinyl alcohol, Static secondary-ion mass spectrometry, Materials science, business.industry, Calibration curve, Analytical chemistry, Infrared spectroscopy, Polymer, Mass spectrometry, Secondary ion mass spectrometry, chemistry.chemical_compound, Optics, chemistry, Liquid crystal, business
Abstract

Dynamic secondary ion mass spectrometry (SIMS) is usually applied to measure depth profiles in inorganic multi-layer systems. SIMS on organic multi-layer samples is highly complicated due to the complex fragmentation of the sample which results in fingerprint of masses representing the components in the sample. Using multivariate statistics, we succeeded to interpret the SIMS spectra and were able to identify layers with different compositions in artificially produced two-layer samples. The method is demonstrated for samples of a poly(isobornylmethacrylate) coating on a polymer dispersed liquid crystal consisting of the nematic liquid crystal (E7) and poly(isobornylmethacrylate). Quantification of the E7 concentration is complicated by evaporation in the vacuum system. Infrared spectroscopy proved that the loss of E7 from poly(isobornylmethacrylate) can be prevented by capping the sample with poly(vinyl alcohol). Cooling to cryogenic temperatures will be required to suppress further evaporation during SIMS analysis. The SIMS depth resolution of a two-layered sample was determined by discriminant function analysis to be 130 nm at a depth of one micrometer, which allows the application of SIMS for a typical optical grating.

Published
2004
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2. Ab initio calculations on the local structure and the 4f-5d absorption and emission spectra of Ce3+-doped YAG

Author

Gracia, J., Seijo, L., Barandiaran, Z., Curulla Ferre, D., Niemantsverdriet, J.W., and Gennip, van, W.J.H

Abstract

The 4f¿5d absorption and emission spectra of Ce3+-doped YAG (Y3Al5O12) are simulated with a quantum chemical ab initio embedded cluster approach applied to Ce3+ substitutional defects of D2 local symmetry. The only empirical information used is the structure of the pure host. The simulated absorption spectrum is calculated with overestimations of 2300–, which became in the luminescence. The three 4f¿5d observed absorptions were assigned and the energies of the two remaining ones, which are hidden by the absorption of the pure host, were predicted. The lowest 5d¿4f emission was found to take place from G5 (22A) and the next emission from G5 (32B3). Good absorption and emission band shapes and relative intensities are obtained. A large underestimation of the Stokes shift is found, which suggests an underestimation of the relaxation on the emitting state.

Published
2008

5. Surface studies of partially fluorinated PMMA by LEIS and XPS

Author

van de Grampel, R.D., Gildenpfennig, A., Gennip, van, W.J.H., Ming, W., Laven, J., Krupers, M.J., Thuene, P.C., Niemantsverdriet, J.W., Brongersma, H.H., Linde, van der, R., Smith, D.W., Materials and Interface Chemistry, and Inorganic Materials & Catalysis

Published
2000

8. Secondary ion mass spectrometry for the identification of polymers with noncharacteristic secondary ions using multivariate statistical analysis

Author

Gennip, van, W.J.H., Thuene, P.C., Dijkstra, J.B., Niemantsverdriet, J.W., Gennip, van, W.J.H., Thuene, P.C., Dijkstra, J.B., and Niemantsverdriet, J.W.

Abstract

Eleven filler-free polymers were investigated by secondary ion mass spectrometry for the identification of polymers with noncharacteristic secondary ions. On a dataset containing the intensities of noncharacteristic hydrocarbon secondary ions, discriminant function analysis and principal components analysis were performed. These statistical methods were used to identify fractions of polymers in depthprofiles of binary polymer blends. The results by the discriminant function analysis show that these secondary ions were sufficient to correctly identify all polymers using leave-one-out correction.

Published
2004

9. The interfaces of poly(p-phenylene vinylene) and fullerene derivatives with Al, LiF, and Al/LiF studied by secondary ion mass spectroscopy and x-ray photoelectron spectroscopy: Formation of AlF3 disproved

Author

Gennip, van, W.J.H., Duren, van, J.K.J., Thuene, P.C., Janssen, R.A.J., Niemantsverdriet, J.W., Gennip, van, W.J.H., Duren, van, J.K.J., Thuene, P.C., Janssen, R.A.J., and Niemantsverdriet, J.W.

Abstract

Two mutually exclusive mechanisms have been proposed to explain the improved electron injection by the insertion of a LiF layer between the metal cathode and the active organic layer of organic photoelectronic devices: the dipole and the doping mechanism. The possibility of the doping mechanism was studied by investigating the interface of poly[2-methoxy-5-(3',7'dimethyl-octyloxyl)-1,4-phenylenevinylene] (MDMO-PPV) or 1-(3-(methoxycarbonyl)propyl)-1-phenyl[6,6]C-61 (PCBM) with Al, LiF, or Al/LiF. In this mechanism, Li dopes the organic layer, after liberation via the reaction Al+3LiF-->AlF3+3Li. If this reaction takes place, AlF3 should be detectable at the surface. However, SIMS measurements showed that AlF3 is not present at the Al/LiF/MDMO-PPV and Al/LiF/PCBM interfaces. This is evidence that the proposed reaction does not occur. Other evidence that the doping mechanism cannot be the general mechanism to explain the enhanced electron injection comes from the presence of LiF on both organic surfaces. XPS measurements indicate that there is a reaction of Al with the carboxylic oxygen of PCBM, and that a LiF layer between PCBM and Al prevents this reaction. (C) 2002 American Institute of Physics

Published
2002

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