UScholar Works
 
Filters: Department: "Chemistry" Collection: "ir_uspace"
151 - 175 of 338
Number of results to display per page
CreatorTitleDescriptionSubjectDate
151 Morse, Michael DavidResonant two-photon ionization spectroscopy of jet-cooled RuCA resonant two-photon ionization study of the jet-cooled RuC molecule has identified the ground state as a 1?+ state arising from the 10?211?25rr42?4 configuration. The 3?i state arising from the 10?211?25rr42?312?1 configuration lies very low in energy, with the 3?3 and 3?2 components lying only 76...1998
152 Miller, Joel StevenCollinear ferromagnetism and spin orientation in the molecule-based magnets M[N(CN)2]2 (M=Co,Ni)Zero-field unpolarized neutron powder diffraction has been used to study the low-T magnetic structure and T-dependent crystal structure of M[N(CN)2]2 (M=Co,Ni). Both compounds show collinear ferromagnetism with spin orientation along the c axis. The results provide the determination of a complete ma...Magnetic; Diffraction; Structure1999
153 Morse, Michael DavidRydberg and pulsed field ionization-zero electron kinetic energy spectra of YOA spectroscopic study of the Rydberg states of YO accessed from particular rotational levels of the A 2II1/2, v=0 state has been combined with a pulsed field ionization, zero electron kinetic energy (PFI-ZEKE) investigation. The results provide accurate values of the ionization energy of YO, ioniz...1999
154 Miller, Joel StevenSpin crossover behavior of [FeII(isoxazole)6][BF4]2--a structural study[FeII(isoxazole)6][BF4]2 undergoes two reversible spin crossover transitions at 91 and 192 K and the single crystal structure determination reveals two different iron sites, Fe1 and Fe2, in a 1 : 2 ratio, with Fe1 attributed to the 91 K transition, and Fe2 attributed to the 192 K transition. This is...Transition; Magnetic; Temperature1999
155 Morse, Michael DavidResonant two-photon ionization spectroscopy of jet-cooled PtSiJet-cooled diatomic PtSi, produced in a laser ablation supersonic expansion source, has been spectroscopically investigated between 17 400 and 24 000 cm-1 by resonant two-photon ionization spectroscopy. Two vibrational progressions are observed and identified as the [15.7]?'=1 ?X 1?+ and [18.5]?'=1 ...1999
156 Armentrout, Peter B.; Morse, Michael DavidRydberg and pulsed field ionization-zero electron kinetic energy spectra of YOA spectroscopic study of the Rydberg states of YO accessed from particular rotational levels of the A²Π½, v=0 state has been combined with a pulsed field ionization, zero electron kinetic energy (PFI-ZEKE) investigation. The results provide accurate values of the ionization energy of YO, ionizati...Ionization energy; Rydberg spectra; Yttrium monoxide1999
157 Miller, Joel StevenMnII(N3)2(pyrazine).A 2-D layered structure consisting of ferromagnetically coupled 1-D {Mn(U-1,1-N3)2}n chainsMn(N3)2(pyz) (pyz = pyrazine) consists of ferromagnetically coupled linear chains of {Mn(N3)2}n comprised of u-1,1-azido bridges together with u-pyz ligands to afford 2-D planar layers.Ferromagnetic; Coupling; Magnetic1999
158 Armentrout, Peter B.Kinetic-energy dependence of competitive spin-allowed and spin-forbidden reactions: V++CS2The kinetic-energy dependence of the V++CS2 reaction is examined using guided ion-beam mass spectrometry. Several different ion sources are used to systematically vary the V+ electronic state distributions and elucidate the reactivities of both the ground and excited state V+ cation.Carbon disulfide; Vanadium ions; Transition metal ions; Bond energies; Endothermic reactions; Exothermic reactions1999
159 Truong, ThanhDirect ab initio dynamics studies of the hydrogen abstraction reactions of hydrogen atom with fluoromethanesA direct ab initio dynamics study on the gas-phase reactions of atomic hydrogen with different fluoromethanes has been carried out. The thermal rate constants were calculated using canonical variational transition state (CVT) theory augmented by multidimensional semiclassical zero and small curvatur...Hydrogen abstraction reactions; Gas-phase reactions; Fluoromethanes; Thermal rate constants; Moller?Plesset perturbation theory; Hybrid density functional theory1999
160 Truong, ThanhImportance of polarization in simulations of condensed phased energetic materialsAn embedded cluster model is used to estimate the molecular dipole moment of crystalline dimethylnitramine (DMNA). The electrostatic potential due to the crystal is included in the calculation via the SCREEP (surface charge representation of the electrostatic embedding potential) approach. The resul...Dimethylnitramine; DMNA; Embedded cluster model1999
161 Wight, Charles AlbertKinetic study of stabilizing effect of oxygen on thermal degradation of poly(methyl methacrylate)The thermal degradation of poly(methyl methacrylate) (PMMA) has been studied in both pure nitrogen and oxygen-containing atmospheres. The presence of oxygen increases the initial decomposition temperature by 70 °C. The stabilizing effect of oxygen may be explained by forming thermally stable radica...Poly(methyl methacrylate); PMMA; Thermal degradation; Isoconversional method1999
162 Wight, Charles AlbertKinetics of thermal decomposition of cubic ammonium perchlorateThe methods of thermogravimetric analysis (TGA) and differential scanning calorimettry (DSC) have been used to study the thermal decomposition of ammonium perchlorate (AP). TGA curves obtained under both isothermal and nonisothermal conditions show a characteristic slowdown at the extents of convers...Thermal decomposition; Cubic ammonium perchlorate; Differential scanning calorimetry1999
163 Truong, ThanhHigh level ab initio and density functional theory evaluation of combustion reaction energetics: NO2 and HONO elimination from dimethylnitramineDimethylnitramine (DMNA) is used as a model system for investigating accurate and efficient electronic structure methods for nitramines. Critical points on the potential energy surfaces of DMNA, CH3NCH3, CH3NCH2, NO2, HONO, and the transition state to HONO elimination were located through geometry o...Dimethylnitramine; DMNA; Nitramines; Combustion reaction energetics1999
164 Miller, Joel StevenCrystal structure and magnetic properties of [Fe{N(CN)2}2(MeOH)2] a 2-D layered network consisting of hydrogen-bonded 1-D chainsA novel 2-D layered network structure [Fe{N(CN)2}2(MeOH)2] was synthesized and characterized by X-ray crystallography, vibrational, and magnetic susceptibility. The neutral 2-D stair-like framework consists of hydrogen-bonded infinite 1-D {Fe[N(CN)2]2} ribbons that pack in a staggered arrangement wh...Solids; Dicyanamide; Ordering1999
165 Morse, Michael DavidResonant two-photon ionization spectroscopy of jet-cooled PdCThe first optical investigation of the spectra of diatomic PdC has revealed that the ground state has ?=0+, with a bond length of r0=1.712?. The Hund?s case (a) nature of this state could not be unambiguously determined from the experimental data, but dispersed fluorescence studies to be reported in...1999
166 Miller, Joel StevenDimetallic complexes derived from a novel dinucleating chelating symmetric triazole ligand; crystal strcutrue,magnetic properties and ESR study of Bis[μ-3,5-diacetlyamino-1,2,4-triazolato-O',N1,N2,O"]bis[nitrato)(aqua)-copper(II)]Reaction of 3,5-diacetylamino-1,2,4-triazole (Hdaat) with copper(II), nickel(II) and cobalt(II) salts yields dinuclear co-ordination compounds, which were spectroscopically characterized. The crystal and molecular structure of one of the compounds, bis[u-3,5-diacetylamino-1,2,4-triazolato-0'_x0001_,...Susceptibility; Orbitals; Compounds1999
167 Miller, Joel StevenEffect of thermal annealing on the ferrimagnetic behavior and ordering of the [MnTXPP]+[TCNE].-.solv (X=F, Cl, Br, I; solv = PhMe, CH2Cl2) family of magnets+5,10,15,20-Tetrakis(4-fluorophenyl)porphyrinatomanganese(III) tetracyanoethenide, [MnTFPP][TCNE], 1F, 5,10,15,20-tetrakis(4-bromophenyl)porphyrinatomanganese(III) tetracyanoethenide, [MnTBrPP][TCNE], 1Br, and 5,10,15,20-tetrakis(4-iodophenyl)porphyrinatomanganese(III) tetracyanoethenide, [MnTIPP][T...Magnetic; Coupling2000
168 Armentrout, Peter B.Collision-induced dissociation dynamics of the [OCS • C2H2]+ complex. A combined experimental and theoretical studyCollision-induced dissociation (CID) of the [OCS • C2H2]+ complex ion with both Xe and Ar over an energy range of 0 to 10 eV in the center of mass frame is studied using a guided ion beam tandem mass spectrometer. The cross sections of the ionic products observed (C,H2S+, OCS+, C2HJ, and S+) are ...Collision-induced dissociation; Competitive shift; Ethylene Sulfide cation; Kinetic shift; Thioketene cation; Potential energy surface2000
169 Miller, Joel Steven; Epstein, Arthur J.Molecule-based magnets - an overviewMolecule-based* magnets are a broad, emerging class of magnetic materials that expand the materials properties typically associated with magnets to include low density, transparency, electrical insulation, and low-temperature fabrication, as well as combine magnetic ordering with other proper...Spin; Magnetization; Magnetic ordering2000
170 Miller, Joel StevenStructure and magnetic properties of meso-tetrakis(2,4,6-trimethylphenyl)porphyrinatomanganese(III) 7,7,8,8-tetracyano 2,5-dimethyl-p-quinodimethanide with a 2.3 K Tc. The first example of cis-coordination of a tetracyano-p-quinodimethanideThe crystal structure of meso-tetrakis(2,4,6-trimethylphenyl)porphyrinatomanganese(III) 7,7,8,8-tetracyano-2,5-dimethyl-p-quinodimethanide, [MnTMesP][DMTCNQ]-2p-C6H4Me2 provides the first example of a cis-1,2-u-coordination motif having an infinite zigzag chain structure. [MnTMesP][DMTCNQ]-2p-C6H4Me...Magnets; Interactions; Coupling2000
171 Miller, Joel StevenNoncollinear antiferromagnetic structure of the molecule-based magnet Mn[N(CN)2]2The crystallographic and magnetic properties of the Mn[N(CN)2]2 compound have been investigated by dc magnetization, ac susceptibility, specific heat, and zero-field neutron diffraction on polycrystalline samples. The magnetic structure consists of two sublattices which are antiferromagnetically cou...Spin; Crystal; Magnetic2000
172 Miller, Joel Steven; Epstein, Arthur J.Magnetic properties and critical behavior of Fe(tetracyanoethylene) 2.x(CH2Cl2): a high-Tc molecule-based magnetWe report magnetic studies of Fe(TCNE)2•x(CH2Cl2), a member of the family of high-Tc molecule-based magnets, M(TCNE)x•y (solvent) (M=V, Mn, TCNE=tetracyanoethelyne). Based on extensive static and dynamic magnetic measurements we show that this system has a complex magnetic behavior, with a mixtu...Solvent; Anisotropy; Spin2000
173 Poulter, Charles DaleCaaX proteases, Afc1p and Rce1p, have overlapping but distinct substrate specificitiesMany proteins that contain a carboxyl-terminal CaaX sequence motif, including Ras and yeast a-factor, undergo a series of sequential posttranslational processing steps. Following the initial prenylation of the cysteine, the three C-terminal amino acids are proteolytically removed, and the newly fo...Proteins; Enzymes; Hydrophobic2000
174 Wight, Charles AlbertThermal analysis of high explosives: liquid state decomposition of RDXNonisothermal thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) have been applied to the thermal decomposition of RDX. Model-free isoconversional analysis of TGA and DSC traces show that RDX primarily evaporates in an open pan with an activation energy of Eα -100 kJ ...RDX; Plastic explosives; Decomposition; Thermogravimetric analysis; Differential scanning calorimetry2000
175 Miller, Joel StevenCluster glass state and photoinduced effects on the freezing dynamics in KxCo[Fe(CN)6]y.ZH2O (x-0.16,y-0.72, z-4.4)The magnetic properties and photoinduced magnetization of a Prussian blue analog, KxCo[Fe(Cn)6]y•ZH2O (x-0.16, y-0.72, z-4.4) were systematically studied. The frequency dependence of the linear ac susceptibility, the irreversibility in the field-cooled/ zero-field-cooled magnetization (MFC /MZFC)...Hexacyanide; Illumination; Temperatures2000
151 - 175 of 338