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Your search keyword '"Vaughan, D. E. W."' showing total 78 results
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78 results on '"Vaughan, D. E. W."'

9. New synthesis and insight into the structure of blue ultramarine pigments

Author

Arieli, D., Vaughan, D. E. W., and Goldfarb, D.

Subjects
Aluminum compounds -- Research, Organic pigments -- Research, Chemistry
Abstract

A new method for preparing blue sodalite pigments, involving high temperature calcination of sodalite samples synthesized with aluminum sulfate and an organic template, is presented. S (sub2)-1 and three types of S(sub 3)(super -1) radicals are identified.

Published
2004

33. High Field ...P ENDOR of MnAlPO...-20: Direct Evidence for Framework Substitution.

Author

Arieli, D. and Vaughan, D. E. W.

Subjects
*MANGANESE, *PULSED nuclear magnetic resonance, *ALUMINUM, *STRUCTURE-activity relationships
Abstract

Looks at a study which investigated the incorporation of manganese (Mn) into framework sites in the aluminophosphate zeotype (AlPO4-n), an analog of sodalite, using pulsed electron nuclear double resonance spectroscopy. Experimental framework of the study; Results; Discussion of the results; Conclusion.

Published
1999
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36. Interactions of Cu(II) Ions with Framework Al in High Si:Al Zeolite Y as Determined from X- and W-Band Pulsed EPR/ENDOR Spectroscopies

Author

Carl, P. J., Vaughan, D. E. W., and Goldfarb, D.

Abstract

A combination of continuous wave (CW) electron paramagnetic resonance (EPR), pulsed EPR, and pulsed electron−nuclear double resonance (ENDOR) techniques were used to obtain structural information about the Cu2+ ions in hydrated, room-temperature evacuated, and dehydrated Cu−Y (Si:Al = 12 and 5) with a particular emphasis on framework Al interactions. W-band 1H ENDOR was used to probe the water ligands, whereas X-band hyperfine sublevel correlation (HYSCORE) spectroscopic measurements were employed to detect 27Al hyperfine couplings. The X-band CW EPR spectra show that a total of three Cu2+ species (A, B, and C) are present in the samples. ENDOR measurements of hydrated and evacuated Cu−Y-12 indicate that species A and B have a complete coordination sphere of water and, on the basis of the absence of 27Al signals in the HYSCORE spectrum, the Cu2+ is not directly bonded to the zeolite framework. Evacuation converted species B to species A. 1H ENDOR spectra combined with simulations show that upon freezing, the equatorial and axial water ligands of species A and B have a distribution of orientations with respect to the Cu−O bond. The CW EPR spectrum of dehydrated Cu−Y-12 shows a single species (species C) and the HYSCORE spectrum exhibits cross-peaks from 27Al with an isotropic coupling, aiso, of 1.5 MHz. Unlike Cu−Y-12, evacuated Cu−Y-5 consists of species A and C, and the HYSCORE spectrum clearly shows a doublet of 27Al cross-peaks with aiso = 3.0 MHz assigned to species C. Upon dehydration, the 27Al coupling decreases to 2.6 MHz. This indicates that in species C the Cu2+ is bound to framework oxygens which are bonded to an Al nucleus. For Si:Al = 5, the zeolite framework becomes negative enough that it can replace water ligands even after mild evacuation. Simulations of 27Al HYSCORE spectra indicate that species C is Cu2+ bound to the framework oxygens primarily near a single Al nucleus with a large quadrupole coupling constant.

Published
2002
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50. Synchrotron X-ray diffraction from a 800 µm3zeolite microcrystal

Author

Eisenberger, P., Newsam, J. M., Leonowicz, M. E., and Vaughan, D. E. W.

Abstract

The brightness of synchrotron X-ray sources, which exceeds that available from conventional generators by many orders of magnitude1–3, provides the possibility of making conventional measurements on much smaller samples. We describe here measurements of Bragg diffracted intensities from two microcrystals of cancrinite, a typical zeolite, performed in order to assess the scope of microcrystal diffraction. Our results demonstrate that many materials previously regarded as polycrystalline can now be studied using well established single-crystal methods at synchrotron facilities.

Published
1984
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