UScholar Works
 
Filters: Department: "Chemistry" Collection: "ir_uspace"
51 - 75 of 338
Number of results to display per page
CreatorTitleDescriptionSubjectDate
51 Morse, Michael DavidSpectroscopy and electronic structure of jet-cooled NiCuDiatomic nickel-copper, NiCu, has been investigated by resonant two-photon ionization spectroscopy in a jet-cooled molecular beam. Six band systems have been identified over the range 11 500-16 500 cm-1. The ground state of NiCu has been determined to be X 2?5/2, with ?"e = 273.01 ? 1.15 cm-1, ?"exe...1988
52 Miller, Joel StevenFormation of a zwitterionic donor-acceptor compound based on N,N,N',N'-tetramethly-p-phenylenediamine and 7,7,8,8-tetracyanoperfluoro-p-quinodimethaneThe reaction of the donor N,N,N',N'- tetramethyl-p-phenylenediamine (TMPD) with the acceptor 7,7,8,8-tetracyanoperfluoro-p-quinodimethane (TCNQF4) has led to the isolation of a novel type of zwitterionic donor-acceptor compound whose structure has been determined by X-ray crystallography.Ccrystals; Single bond1988
53 Miller, Joel StevenConvenient synthesis of C5(CD3)5H. synthesis and characterisation of Fe{n5-C5(CD3)5}2The large scale synthesis of deuterio(pentamethylcyclopentadiene), C5(CD3)5H ([2H30]Cp*H), and subsequent synthesis of [2H30][Fe(n|-Cp*)2] is described, together with i.r., Raman, and solid state 2H n.m.r. spectroscopic characterisation.Organometallic; Catalytic1988
54 Armentrout, Peter B.Energetics and dynamics in the reaction of Si+ with SiF4. Thermochemistry of SiFx and SiFx+ (x=1,2,3)The title reaction is studied using guided ion beam mass spectrometry. Absolute reaction cross sections are measured as a function of kinetic energy from thermal to 40 eV, and three endothermic product channels are observed. The dominant SiF+ + SiF3 channel is only slightly endothermic, while the ...Silicon fluoride; Ion-molecule reactions; Kinetic energy; Threshold behavior; Endothermic reactions1988
55 Miller, Joel Steven; Epstein, Arthur J.Quest for a polymeric ferromagnet: a new polymorph of 1,4-bis(2,2,6,6-tetramethyl-4-oxy-4-piperidyl-1-oxy)butadiyne (invited)A new polymorph of 1,4-bis(2,2,6,6-tetramethyl-4-oxy-4-piperidyl-l-oxy) butadiyne has been prepared and characterized by x-ray diffraction, infrared and Raman spectroscopies, and magnetic susceptibility. Unlike t h e Pccn-a phase, the B phase belongs to the Pca2y1 space group [a = 14.265(1) A(o),b ...Molecular; Magnetic; Thermal1988
56 Morse, Michael DavidResonant two-photon ionization spectroscopy of jet-cooled Pt?The gas phase optical spectrum of jet-cooled Pt? has been investigated over the range of 11 300 to 26 300 cm -1 using resonant two-photon ionization spectroscopy in combination with time-of-flight mass spectrometry. Numerous vibronic bands are observed. Analysis of the data gives the location of som...1988
57 Armentrout, Peter B.Collision-induced dissociation processes of Nb4+ and Fe4+: fission vs. evaporationDespite the extensive effort devoted to research on gasphase metal clusters, quantitative thermodynamic data on such species are scarce. Such information is key to understanding and predicting the physical and chemical properties of clusters. Presently, bond energies are available primarily for tr...Metal clusters; Nobium ions; Iron ions; Fission; Evaporation1988
58 Miller, Joel Steven; Epstein, Arthur J.Ferromagnetism in molecular materials: decamethylferrocenium tetracyanoethanide [DMeFc][TCNE] (invited)Ferromagnetism has only recently been observed in molecular materials. We present here a summary of the ferromagnetic phenomena observed in the molecular charge transfer salt, decamethylferrocenium tetracyanoethanide (DMeFc) (TCNE), and related compounds. A spontaneous magnetization is observed i...Magnetic; Magnetization1988
59 Miller, Joel Steven; Epstein, Arthur J.New polymorph of 4,4'-(Butadiyne-1,4-diyl)-bis-(2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl)A new polymorph of the title diradical has been characterized by X-ray diffraction, vibrational spectroscopy, and magnetic susceptibility; its radiation induced polymerization has not been achieved, but thermal treatment turns the crystals black and explosive decomposition occurs at-140 °C.Ferromagnetic; Polymerization; Magnetic1988
60 Morse, Michael DavidResonant two-photon ionization spectroscopy of jet-cooled NiPtResonant two-photon ionization spectroscopy of jet-cooled NiPt has been used to investigate the possibility of <f-electron contributions to the bonding in this species. Based on an abrupt onset of predissociation, the bond strength of NiPt is assigned as D0 (NiPt) = 2.798 ? 0.003 eV. Comparisons of ...1989
61 Miller, Joel Steven; Epstein, Arthur J.Optical properties of quinolinium tetracyanoquinodimethanide, [Qn(TCNQ)2] and (N-methylphenazinium)x(phenazine)1-x (tetracyanoquinodimethane) [(NMP)x(Phen)1-x(TCNQ)]We present here optical-absorption data of quinolinium ditetracyanoquinodimethanide [Qn(TCNQ)2] and (N-methylphenazinium)x(phenazine)1-x(tetracyanoquinodimethanide) [(NMP)x(Phen)1-x(TCNQ)] for 0.5 <_x<_ 0.6. These materials span the range of electronic structure from commensurate, to commensurate ...Commensurate; Lattice; Electron1989
62 Morse, Michael DavidLaser excitation spectroscopy of the A and B states of jet-cooled copper dimer: evidence for large electronic isotope shiftsFluorescence excitation spectra recorded for the A-X system of jet-cooled Cu2 show conclusive evidence of a ?? = 0 transition, and the A state is thereby definitively assigned as ??u+. A previous assignment of the B state as ??u+ is confirmed, but the vibrational levels of this state are complicated...1989
63 Miller, Joel StevenStructural and magnetic characterization of a- and B-2,4-hexadiyne-1,6-diyl Bis(2,2,5,5-tetramethyl-1-oxyl-3-pyrroline-3-carboxylate) and its thermal degradation productThe search for ferromagnetic organic compounds and polymers is the focus of contemporary research.1 - 5 Polymerization of di-iminoxyl diacetylene monomers has been suggested as a means to prepare a high spin potentially ferromagnetically coupled polymers3 and the thermal, photochemical, and glow di...Ferromagnetic; Magnetization; Polymers1989
64 Armentrout, Peter B.Collision-induced dissociation of Fen+ (n=2-10) with Xe: ionic and neutral iron binding energiesCross sections for collision-induced dissociation (CID) of Fen+ with Xe, 2≤n≤10, are presented. Experiments were performed on a newly constructed guided ion beam mass spectrometer, the design and capabilities of which are described in detail. The single mechanism for dissociation of iron cluster...1989
65 Armentrout, Peter B.Reactions of Ar+, Ne+, and He+ with SiF4 from thermal energy to 50 eV c.m.Guided ion-beam techniques are used to measure the cross sections for reaction of SiF4 with Ar+, Ne+, and He+ from thermal to 50 eV. Charge transfer followed by loss of F atoms are the sole processes observed. All SiFx + (x = 0-4) products are observed, except for SiF4 + from reaction with Ne+ and ...Ion-molecule reactions; Tetrafluorosilane; Rare gas ions; Endothermic reactions; Plasma systems1989
66 Armentrout, Peter B.Oxidation reactions at variably sized transition metal centers: Fen+ and Nbn+ + O2 (N=1-3)Cross sections for the reactions of Fen+ and Nbn+ (n = 1-3) with 02 are measured as a function of kinetic energy over a range of 0 to > 10 eV. In all systems, analysis yields insight into the kinetics and thermochemistry of the oxidation processes. Nbn+ reaction with 02 exothermically near the Lange...Metal clusters; Nobium ions; Iron ions; Exothermic reactions1989
67 Morse, Michael DavidSpectroscopy and electronic structure of jet-cooled GaAsAn optical spectrum, obtained by resonant two-photon ionization spectroscopy, is reported for jet-cooled diatomic gallium arsenide. The ground state is identified as X??-, deriving from a ??rr? molecular configuration, and is characterized by ?" = 215 cm-1, ?"exe" = 3 cm-1, and r0' = 2.53 ? 0.02 ?. ...1989
68 Armentrout, Peter B.Spin-orbit state-selected reactions of Xe+(2P3/2 and 2P1/2) with H2, D2, and HDSpin-orbit state-selected reactions of X e + (2Pj ), j = 3/2 and 1/2, with isotopic molecular hydrogen (H2 , D2 , and HD) to form X e H + and XeD + are studied using guided ion beam mass spectrometry. Reaction cross sections are determined as a function of reactant kinetic energy from near thermal ...Spin-orbit; Xenon ions; Hydrogen isotopes; Isotope effects; Ion-molecule reactions1989
69 Miller, Joel Steven; Epstein, Arthur J.Specific heat of decamethylferrocenium tetracyanoethanide (DMeFc)(TCNE)We report the specific heat C(T) of (DMeFc)(TCNE) for temperatures 3 K < T < 50 K. We observe an anomaly at Tc-4.82 K corresponding to a transition to a three-dimensional (3D) macroscopic ferromagnet. A broad maximum at = 15 K corresponds to an exchange interaction of J = 35 K along the chain axis. ...Temperature; Ferromagnetic; Magnetic1989
70 Poulter, Charles DaleFarnesyl diphosphate synthetase: molecular cloning, sequence, and expression of an essential gene from Saccharomyces cerevisiaeFarnesyl diphosphate (FPP) synthetase is a key enzyme in isoprenoid biosynthesis which supplies C15 precursors for several classes of essential metabolites including sterols, dolichols, and ubiquinones. The structural gene for FPP synthetase was isolated on a 4.5-kilobase EcoRI genomic restriction f...Genetics; Transferases; Dimethylallyltranstransferase/biosynthesis1989-11-15
71 Poulter, Charles DaleIsopentenyl diphosphate:dimethylallyl diphosphate isomerase. An improved purification of the enzyme and isolation of the gene from Saccharomyces cerevisiae.Isopentenyl diphosphate:dimethylallyl diphosphate isomerase (IPP isomerase) is an enzyme in the isoprenoid biosynthetic pathway which catalyzes the interconversion of the primary five-carbon homoallylic and allylic diphosphate building blocks. We report a substantially improved procedure for purific...Amino Acid Sequence; Base Sequence; Chromatography, Gel; Chromatography, Ion Exchange1989-11-15
72 Armentrout, Peter B.Dissociative charge transfer reactions of Ar+, Ne+, and He+ with CF4 from thermal to 50 eVGuided ion-beam techniques are used to measure the cross sections for reaction of CF4 with Ar+, Ne+, and H e + from thermal to 50 eV. Dissociative charge transfer followed by successive loss of F atoms are the major processes observed. Only CFx+ (x = 1,2,3) products are observed in the reactions of ...Ion-molecule reactions; Transfer reactions; Carbon tetrafluoride; Rare gas ions; Exothermic reactions; Endothermic reactions; Plasma systems1990
73 Morse, Michael DavidSpectroscopy and electronic structure of jet-cooled NiPd and PdPtResonant two-photon ionization spectroscopy of jet-cooled NiPd and PdPt has revealed a dense vibronic spectrum for NiPd and a much more sparse spectrum for PdPt. Four vibrational progressions have been identified for NiPd, and three have been located for PdPt. High resolution investigations of NiPd...1990
74 Morse, Michael DavidSpectroscopy and electronic structure of jet-cooled Al?Resonant two-photon ionization spectroscopy has been used to study the jet-cooled Al? molecule. The ground state has been conclusively demonstrated to be of 3IIu symmetry, deriving from the ???rr?u electronic configuration. High resolution studies have established the bond length of the X?IIu state ...1990
75 Armentrout, Peter B.Kinetic energy dependence of dissociative charge-transfer reactions of He+, Ne+, Ar+, Kr+, and Xe+ with silaneGuided ion-beam techniques are used to measure the cross sections as a function of kinetic energy for reaction of SiH4 with He +, Ne +, Ar +, Kr +, and Xe +. State-specific data for the 2P3/2 ground spin-orbit states of Kr+ and Xe+ are also obtained.Silane; Charge-transfer reactions; Ion-molecule reactions; Ion energy; Rare gas ions; Plasma systems1990
51 - 75 of 338