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Creator | Title | Description | Subject | Date |
226 |
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Morse, Michael David | Optical spectroscopy of jet-cooled NiSi | The electronic states of gaseous diatomic NiSi have been investigated using the combined techniques of resonant two-photon ionization spectroscopy, dispersed fluorescence spectroscopy, and density functional computations. A single electronic band system, designated as the [8.0]1?X 1?+ system, has be... | | 2003 |
227 |
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Armentrout, Peter B. | Guided ion beam studies of the reactions of Nin+ (n=2-18) with O2: nickel cluster oxide and dioxide bond energies | The kinetic energy dependences of the reactions of Nin + (n=2 - 18) with O2 are studied in a guided ion beam tandem mass spectrometer. A variety of NimO2+, NimO+, and Nim+ product ions, where m<n, are observed, with the dioxide cluster ions dominating the products for all larger reactant cluster io... | Metal clusters; Nickel oxide; Nickel dioxide; Bond energies; Collision-induced dissociation; Exothermic reactions | 2003 |
228 |
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Armentrout, Peter B. | Kinetic energy dependence of association reactions. A new thermokinetic method for large systems | The reactions of bare alkali metal ions (M+5Li+, Na+, or K+) with dimethoxyethane (CH3OCH2CH2OCH3 , (DXE) are studied using guided ion beam tandem mass spectrometry. The bimolecular reaction forms an associative M1(DXE) complex that is long-lived and dissociates back to the reactants. The kinetic en... | Collision-induced dissociation; Association reactions; Bond energies; Dimethoxyethane; Alkali metal ions | 2003 |
229 |
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Miller, Joel Steven; Epstein, Arthur J. | Anomalous magnetoresistance in high-temperature organic-based magnetic seminconducting V(TCNE)x films | Anomalous positive magnetoresistance (MR) in high temperature organic-based magnet V(TCNE)x (TCNE=tetracynoethylene) thin films is reported. MR increases linearly with applied magnetic field and shows a maximum at the ferrimagnetic ordering temperature. The suggested roles of oppositely spin pola... | Spin; Ferrimagnetic; Resistance | 2003 |
230 |
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Morse, Michael David | Dispersed fluorsecence spectroscopy of AINi, NiAu, and PtCu | Dispersed fluorescence studies of AlNi, NiAu, and PtCu have been performed, providing spectroscopic information about the ground and low-lying excited electronic states. Vibrational frequencies are reported for the ground X 2?5/2 state of all three molecules. In the case of AlNi, fluorescence to all... | | 2003 |
231 |
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Poulter, Charles Dale | Catalytic mechanism of Escherichia coli isopentenyl diphosphate isomerase involves Cys-67, Glu-116, and Tyr-104 as suggested by crystal structures of complexes with transition state analogues and irreversible inhibitors | Isopentenyl diphosphate (IPP):dimethylallyl diphosphate (DMAPP) isomerase is a key enzyme in the biosynthesis of isoprenoids. The reaction involves protonation and deprotonation of the isoprenoid unit and proceeds through a carbocationic transition state. Analysis of the crystal structures (2 A) of ... | Catalytic Domain; Crystallography; Organophosphorus Compounds | 2003-04-04 |
232 |
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Poulter, Charles Dale | Enzymes encoded by the farnesyl diphosphate synthase gene family in the big sagebrush Artemisia tridentata ssp. spiciformis | Farnesyl diphosphate synthase catalyzes the sequential head-to-tail condensation of two molecules of isopentenyl diphosphate with dimethylallyl diphosphate. In plants the presence of farnesyl diphosphate synthase isozymes offers the possibility of differential regulation. Three full-length cDNAs enc... | Amino Acid Sequence; Base Sequence; Molecular Sequence Data | 2003-08-22 |
233 |
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Miller, Joel Steven | Zero field splitting, field-dependent magnetization of mixed-valent S = 3/2 Diruthenium(II,III) tetracarboxylates | The 2 K field-dependent magnetization, M(H), of S = 3/2 [RunII/III2(OAc)4]+ was studied. [RuII/III 2(OAc)4]+ exhibits an unusually low magnetization with respect to that predicted by the classical Brillouin function. This reduced value is a consequence of the large anisotropy arising from the large ... | Spin; Coupling; Expressions | 2004 |
234 |
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Miller, Joel Steven | Synthesis, structural, and magnetic characterization of substituted benzoimidazole-l-yl N,N'-dioxides | The crystal structures, EPR spectra and magnetic properties of the novel halogen- and cyano-substituted nitronyl nitroxide radicals 2-(2,6-dichlorophenyl)benzimidazolyl N,N'-dioxide, 6, 2-(2,6-difluorophenyl)benzimidazolyl N,N'- dioxide, 7, 2-(2-chloro-6-fluorophenyl)benzimidazolyl N,N'-dioxide, 8,... | Organic; Ferromagnetic; Coupling | 2004 |
235 |
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Miller, Joel Steven; Epstein, Arthur J. | Local structural order in the disordered vanadium tetracyanoethylene room-temperature molecule-based magnet | We determined the vanadium oxidation state and local coordination environment in disordered samples of magnetic V[TCNE]x(x=2) prepared by chemical vapor deposition (CVD). Systematic studies of the x-ray absorption near-edge structure (XANES) in this material and reference compounds show that V ions ... | Magnetic; Solvent; Structure | 2004 |
236 |
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Morse, Michael David | Vibronic spectroscopy of unsaturated transition metal complexes: CrC?H, CrCh?, and NiCH? | Vibronically resolved resonant two-photon ionization and dispersed fluorescence spectra of the organometallic radicals CrC2H, CrCH3 , and NiCH3 are reported in the visible and near-infrared wavelength regions. For CrC2H, a complicated vibronic spectrum is found in the 11 100?13 300 cm-1 region, with... | | 2004 |
237 |
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Miller, Joel Steven; Epstein, Arthur J. | Ferrimagnetic resonance in films of vanadium [tetracyanoethanide]x, grown by chemical vapor deposition | Ferrimagnetic resonance (FMR) measurements in thin films of V[TCNE]x grown by chemical vapor deposition exhibit a series of sharp lines at 300 K. The orientational dependence of these lines is a result of the sample geometry provided the magnetization tracks the applied magnetic field. The FMR inten... | Spin; Anisotropy; Magnetization | 2004 |
238 |
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Armentrout, Peter B. | Probes of spin conservation in heavy metal reactions: experimental and theoretical studies of the reactions of Re+ with H2, D2, and HD | A guided ion beam tandem mass spectrometer is used to examine the kinetic energy dependence of reactions of the third-row transition metal cation, Re1, with molecular hydrogen and its isotopologues. A flow tube ion source produces Re1 in its 7S3 electronic ground state. | Endothermic reactions; Transition metal ions; Rhenium ions; Dihydrogen | 2004 |
239 |
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Miller, Joel Steven; Epstein, Arthur J. | Anomalous relaxation in a quasi-one-dimensional fractal cluster glass | The low-temperature spin glass state of the quasi-1D organic-based magnet [MnTPP]+[TCNE]- .x(1,3-C6H4Cl2) has unusually long relaxation times due to frustration induced by dipole-dipole interactions between fractal spin clusters. This long relaxation is investigated with in-field relaxation measurem... | Sweep rate; Bifurcation; Magnetization | 2004 |
240 |
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Armentrout, Peter B. | Reaction of Cu+ with dimethoxyethane: competition between association and multiple dissociation channels | The reaction of Cu1 with dimethoxyethane (DXE) is studied using kinetic-energy dependent guided ion beam mass spectrometry. The bimolecular reaction forms an associative Cu1(DXE) complex that is long-lived and dissociates into several competitive channels: C4H9O2 11CuH, Cu1(C3H6O)1CH3OH, back to rea... | Dimethoxyethane; Copper ions; Association reactions; Collision-induced dissociation; Phase state theory | 2004 |
241 |
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Armentrout, Peter B. | Mechanism of proton exchange: guided ion beam studies of the reactions, H(H2O)n+ (n=1-4) + D2O and D(D 2O)n+ (n=1-4) + H2O | Reactions of protonated water clusters, H(H2O)n+ (n=1-4) with D2O and their "mirror" reactions, D(D2O)n+ (n=1-4) with H2O, are are studied using guided-ion beam mass spectrometry. Absolute reaction cross sections are determined as a function of collision energy from thermal energy to over 10 eV. | Collision-induced dissociation; Proton exchange; Protonated water clusters; Exothermic reactions; Deuterium oxide | 2004 |
242 |
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Morse, Michael David | Optical spectroscopy of RuC: 18 000-24 000 cm ?1 | The optical spectrum of diatomic RuC has been recorded from 17 800 to 24 200 cm-1. Three previously unidentified excited electronic states were analyzed and identified as having ?'=0, ?'=2, and V853. The ?'=3 state was determined to be a 3?3 state that is suggested to arise from a mixture of the 10?... | | 2004 |
243 |
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Armentrout, Peter B. | Methane activation by nickel cluster cations, Nin+ (n=2-16): reaction mechanisms and thermochemistry of cluster-CHx (x=0-3) complexes | The kinetic energy dependences of the reactions of Nin+ (n=2-16) with CD4 are studied in a guided ion beam tandem mass spectrometer over the energy range of 0-10 eV. The main products are hydride formation NinD1, dehydrogenation to form NinCD2 1 , and double dehydrogenation yielding NinC1. | Nickel ions; Metal clusters; Deuterated methane; Collision-induced dissociation; Endothermic reactions; Bond energies; Dehydrogenation | 2004 |
244 |
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Voth, Gregory Alan; Sarofim, Adel F. | Identification of pathways for polyaromatic growth using molecular dynamics | Reaction pathways for polyaromatic growth in combustion environments are explored theoretically using molecular dynamic techniques. The reaction systems considered include cyclization reactions that involve H atom migration. Specifically we examine the absorption of acetylene on an aromatic ring rad... | | 2004 |
245 |
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Baehr, Wolfgang; Prestwich, Glenn D. | Photoreceptor cGMP phosphodiesterase delta subunit (PDEdelta) functions as a prenyl-binding protein | Bovine PDEdelta was originally copurified with rod cGMP phosphodiesterase (PDE) and shown to interact with prenylated, carboxymethylated C-terminal Cys residues. Other studies showed that PDEdelta can interact with several small GTPases including Rab13, Ras, Rap, and Rho6, all of which are prenylate... | Fluorescence Resonance Energy Transfer; GTP Phosphohydrolases; Immunohistochemistry | 2004 |
246 |
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Stang, Peter J. | Incorporation of flexible pyridine-functionalized ligands into discrete supramolecules via coordination-driven self-assembly | Flexible, pyridine-functionalized ligands were self-assembled into discrete supramolecules of differing stoichiometries upon combination with various organoplatinum molecules. They are characterized by electrospray ionization mass spectrometry, 31P(iHI and 'H NMR. Despite its inherent flexibility, 3... | Self-assembly; Coordination-driven; Transition-metal-mediated; Flexible ligands; Pyridyl ligands; Supramolecules | 2004 |
247 |
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Miller, Joel Steven | Crystal engineering or crystal mysticism? A case study | The de novo design and synthesis of a crystalline motif of a substance is a holy grail for a growing number of organic and inorganic synthetic chemists. Achievement of targeted architectural arrangements is less reliable as the complexity increases. Simple substitution of, for example, alkyl penda... | Synthesis, Structure, Chemistry | 2005 |
248 |
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Armentrout, Peter B. | Guided ion-beam studies of the reactions of Con + (n=2-20) with O2: cobalt cluster-oxide and -dioxide bond energies | The kinetic-energy dependence for the reactions of Con + (n=2-20) with O2 is measured as a function of kinetic energy over a range of 0 to 10 eV in a guided ion-beam tandem mass spectrometer. A variety of Com+ , ComO+, and ComO2 + (m<n) product ions is observed, with the dioxide cluster ions domina... | Metal clusters; Cobalt ions; Collision-induced dissociation; Bond energies; Exothermic reactions; Endothermic reactions | 2005 |
249 |
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Voth, Gregory Alan | Systematic coarse-graining of nanoparticle interactions in molecular dynamics simulation | A recently developed multiscale coarse-graining procedure [Izvekov, S.; Voth, G. A. J. Phys. Chem. B 2005, 109, 2469] is extended to derive coarse-grained models for nanoparticles. The methodology is applied to C60 and to carbonaceous nanoparticles produced in combustion environments. The coarse-gra... | Systematic coarse-graining; Multiscale coarse-graining | 2005 |
250 |
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Armentrout, Peter B. | Guided ion-beam studies of the kinetic-energy-dependent reactions of Con+ (n=2-16) with D2: cobalt cluster-deuteride bond energies | The kinetic-energy-dependent cross sections for the reactions of Con + (n=2-16) with D2 are measured as a function of kinetic energy over a range of 0-8 eV in a guided ion-beam tandem mass spectrometer. The observed products are ConD+ for all clusters and ConD2+ for n=4,5,9-16. | Cobalt ions; Metal clusters; Deuteride; Collision-induced dissociation; Endothermic reactions; Bond energies | 2005 |