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Chemistry

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1999

Articles 1 - 5 of 5

Full-Text Articles in Physical Sciences and Mathematics

Development And Student Use Of Web-Based Prelabs In Analytical Chemistry Courses, Mark Anderson, Brian Tissue Sep 1999

Development And Student Use Of Web-Based Prelabs In Analytical Chemistry Courses, Mark Anderson, Brian Tissue

Mark R. Anderson

No abstract is currently available.

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Ab Initio Calculation Of 81Br Nqr Transition Frequencies Of Brominated Aromatics (Flame Retardants), Chris R. Harwell, Anthony A. Mrse, Leslie G. Butler, Randall W. Hall Sep 1999

Ab Initio Calculation Of 81Br Nqr Transition Frequencies Of Brominated Aromatics (Flame Retardants), Chris R. Harwell, Anthony A. Mrse, Leslie G. Butler, Randall W. Hall

Randall W. Hall

Brominated aromatics, used extensively as flame retardants, have been studied with 81Br nuclear quadrupole resonance (NQR) spectroscopy. NQR requires lengthy frequency searches because 81Br NQR transition frequencies in brominated aromatics are spread over a wide (40 MHz) range. We investigate the ability of ab initio calculations to narrow this search range by predicting 81Br NQR transition frequencies for a series of brominated aromatics, using restricted Hartree−Fock (RHF) and Becke's three-parameter Lee−Yang−Parr density functional theory hybrid method (B3LYP). Basis sets used are of double and triple-ζ quality with varying degrees of polarization included on bromine. Geometries are the isolated molecules, with …

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Voltammetry Of Metallofullerenes And Higher Fullerenes, Mark Anderson, Harry Dorn, Steven Stevenson, Susanne Dana May 1999

Voltammetry Of Metallofullerenes And Higher Fullerenes, Mark Anderson, Harry Dorn, Steven Stevenson, Susanne Dana

Mark R. Anderson

No abstract is currently available.

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Changes In The Fermi Surface At The Magnetization Reorientation Transition In Fe/Cu(100), Reginaldt H. Madjoe, Alexey N. Koveshnikov, Christopher Harwell, Randall W. Hall, Roger L. Stockbauer, Richard L. Lutz Dec 1998

Changes In The Fermi Surface At The Magnetization Reorientation Transition In Fe/Cu(100), Reginaldt H. Madjoe, Alexey N. Koveshnikov, Christopher Harwell, Randall W. Hall, Roger L. Stockbauer, Richard L. Lutz

Randall W. Hall

We present a study of the evolution of the valence bandstructure of Fe/Cu(100) as a function of Fe coverage in the 0–12 monolayer range. Angle-resolved photoelectron spectroscopy was used to probe the valence electronic structure and to extract Fermi surface contours as a function of increasing Fe coverage. The first few monolayers show Fe-induced densities of states that are significantly different from those in thicker films. At 5 ML, distinct changes occur in the Fermi surface, where a magnetization reorientation transition has been observed previously.

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Single-Crystal 27Al Nmr Of Andalusite And Calculated Electric Field Gradients: The First Complete Nmr Assignment For A 5-Coordinate Aluminum Site, Pamela L. Bryant, Chris R. Harwell, Katherine Wu, Frank R. Fronczek, Randall W. Hall, Leslie G. Butler Dec 1998

Single-Crystal 27Al Nmr Of Andalusite And Calculated Electric Field Gradients: The First Complete Nmr Assignment For A 5-Coordinate Aluminum Site, Pamela L. Bryant, Chris R. Harwell, Katherine Wu, Frank R. Fronczek, Randall W. Hall, Leslie G. Butler

Randall W. Hall

Andalusite, Al2SiO5, contains 5- and 6-coordinate aluminum sites, and is a preeminent model for 27 Al NMR spectroscopy. We describe a combined NMR, crystallography, and theory project:  single-crystal 27 Al NMR spectra at 298 K, the crystal structure of andalusite at 115 K, and electric field gradient calculations. The low-symmetry 5-coordinate site is a stiff test of the computational methods. In addition, the chemical shift tensor is measured for the 5-coordinate site. The small body of 27 Al NMR data, especially for rare 5-coordinate sites, inspires the calculation of NMR parameters. We explore the accuracy of two approaches for 27 …

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