- Formation, characterization, structure and bonding analysis of the metal-carbon bond OM-(η6-C6H6) (M = Sc, Ti) complexes in solid matrix: Infrared spectroscopic and theoretical study
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The reactions of ScO and TiO molecules with benzene have been studied in solid argon with infrared absorption spectroscopy combining with theoretical calculations. Laser-evaporation of bulk higher oxide targets prepared the scandium and titanium monoxide
- Zhao, Yanying,Zhang, Yuchen,Liu, Xin,Fan, Kexue,Zheng, Xuming
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- A molecular-beam-optical and radio frequency-optical double-resonance study of the A2Πr-X2Σ+ band system of scandium monoxide
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A molecular-beam-optical and rf-optical double-resonance study of the A 2Π (v' = 0-2) -X 2Σ+ ( v = 0-2 ) band systems of gas phase scandium monoxide has been performed.No localized perturbations in the X2Σ+ state have been observed but strong perturbations in the A2Πr ( v = 1 ) state were detected.Quantum numbers for the optical spectrum could only be assigned assuming a negative value for the excited state Λ-doubling-type magnetic hyperfine parameter, contrary to current theoretical understanding of this interaction.The ground state magnetic hyperfine parameters can be interpreted in terms of ab initio models for the electronic states of ScO whereas the spin-rotation parameters cannot.
- Childs, W. J.,Steimle, T. C.
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- Nonequilibrium product distributions observed in the multiple collision chemiluminescent reaction of Sc with NO2. Perturbations, rapid energy transfer routes and evidence for a low-lying reservoir state
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Nitrogen dioxide reacts with scandium to yield the B 2Σ+-X 2Σ+ spectrum ScO.This reaction has been characterized from 10-5 to 1 Torr in order to study relaxation and rapid intramolecular E-E transfer among ScOexcited states.At the lowest pressures, a ground state metal atom interacts with a tenuous atmosphere of oxidant gas (beam-gas configuration).These single collision studies are extended in a controlled manner to higher pressure by entraining the metal atoms in argon and subsequently carrying out the oxidation of this mixture.At all pressures, the measured B 2Σ+ vibrational populations follow a markedly non-Boltzmann distribution.At the lowest pressures, the formation of ScO B 2Σ+ results directly from the reaction Sc+NO2->ScO*+NO.At higher pressures, the B 2Σ+ state is also populated via rapid intramolecular energy transfer from long-lived, weakly emitting reservoir states via the sequence Sc+NO2+Ar->ScO(res)+NO+Ar and ScO(res)+Ar->ScO(B 2Σ+)+Ar.Spin orbit and Coriolis interactions in ScO connect rovibronic levels of B 2Σ+ and low-lying 4Πr or 2Πi reservoir states resulting in the observation of substantial perturbations in B 2Σ+.Collisional energy transfer is particularly efficient for the most strongly perturbed levels of the B 2Σ+ state.This energy transfer is manifest by the apperance of extra band heads representing normally forbiden (small electronic transitionmoment or Franck-Condon factor) reservoir state -ground state transitions which become allowed because of a small admixture of B 2Σ+ character.The relative intensities of the extra and main B 2Σ+-X 2Σ+ transitions are strongly dependent on argon buffer gas pressure.A quantitative description of this dependence gives an estimate for the amount of mixing between the reservoir state and B 2Σ+ and for the rate of energy transfer between these two states.Collisional transfer to ScO B 2Σ+ υ'=3-9 is found to proceed at rates which for certain levels approach 100 times gas kinetic.The effects observed in ScO demonstrate that the excited states of this molecule interact in the presence of a collision partner as if they were large diffuse entities.These effects are not pathological.This behavior may have important implications for the modeling of energy systems as well as the ability to create population inversions requisite for the construction of visible chemical laser systems.
- Gole, J. L.,Pace, S. A.
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- Temperature dependent study of the kinetics of Sc(a 2D3/2) with O2, N2O, CO2, NO and SO2
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The gas phase reactivity of Sc(a 2 D3/2) with O2, N2O, CO2, NO and SO2 in the temperature range 298-523 K is reported. The bimolecular rate constants are described in Arrhenius form by k(O2) = (1.7 ± 0.4) X 10-10 exp( - 7.9 ± 0.7 kJ/mol/RT) cm3 s-1, k(N2O) = (1.7 ± 0.3) X 10~10-10 exp(-12.0 ± 0.6 kJ/mol/RT) cm3 S-1, k(CO2) = (7.3 ± 1.3) X 10-11 exp( - 12.3 ± 0.6 kJ/mol/RT) cm3 s-1 where the uncertainties are ±2σ. The rate constants with NO and SO2 were temperature insensitive with room temperature rate constants of 1.5 X 10-11 and 2.0 X 10-10 cm3s-1, respectively. The disappearance rates for all the reactants are independent of total pressure indicating a bimolecular abstraction mechanism.
- Campbell, Mark L.,Hooper, Kelli L.,Koelsch, Erica J.
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- Matrix-isolation fourier transform infrared and theoretical studies of laser-ablated Sc atom reactions with water molecules
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Laser-ablated Se atoms have been reacted with water molecules during condensation with argon at 11 K. In agreement with previous thermal atom reactions, absorptions at 1482.6 and 713.0 cm-1 are assigned to the HScOH molecule formed via an inser
- Zhang, Luning,Dong, Jian,Zhou, Mingfei
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- Kinetics of Neutral Transition-Metal Atoms in the Gas Phase: Oxidation of Sc(a2D), Ti(a3F), and V(a4F) by NO, O2, and N2O
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The oxidation kinetics of gas-phase, ground-state Sc(a2D), Ti(a3F), and V(a4F) atoms by NO, O2, and N2O is studied in 0.80 Torr of He buffer gas at 300 +/- 5 K.The metal atoms are created in a hollow cathode sputtering source before entering a fast flow reactor.The reactions are monitored by laser-induced fluorescence of the metal atom reactant.All nine M + OX -> MO + X bimolecular oxygen atom transfer reactions are inefficient at 300 K with rate constants in the range 0.45 x 10-12 to 10 x 10-12 cm3s-1.This indicates activation energies not larger than2-4 kcal mol-1 in all cases.The substantial range of reaction rates for a particular metal with the three different oxidants contrasts with the remarkable similarity of rates for all three metal atoms with each oxidant.The rate constants for reaction of each metal with the three oxidants fall in the order kNO > kO2 > kN2O, opposite to the normal expectation of decreasing activation energy with increasing exothermicity.The rate constant ordering kSc > kV > kTi for each oxidant and the small activation energies are interpreted in terms of an electron-transfer mechanism from neutral M + OX reactant surfaces to ion-pair M+O- + X product surfaces.
- Ritter, David,Weisshaar, James C.
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p. 4907 - 4913
(2007/10/02)
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- Trends in the Optical Signatures for Transition-Metal Oxide Carbonyl Complexes. Evaluation of Transition-Metal Carbonyl, M(CO)x, Binding Energies
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Transition-metal atoms entrained in argon, helium, and CO are oxidized with ozone (O3) and nitrogen dioxide (NO2) to study the nature of the metal atom complexation with CO.We establish a method for evaluating M-CO binding energies through comparison of the chemiluminescent emission from the oxidation of argon- and CO-entrained transition-metal atoms.These studies have thus far yielded Ebinding(Ti(CO)x) ca. 1.75 eV and Ebinding(NiCO) ca. 1.10 eV, the latter in excellent agreement with previous experimental and theoretical evaluations of the Ni-CO bond energy.We identify the optical signatures for transition-metal oxide carbonyl (MOCO) complexes formed in the oxidation of M(CO) complexes.We outline trends in the nature of the observed metal oxide complex emissions.The current study suggests a method for obtaining the spectra of transition-metal carbonyl (M(CO)x, x=1,2) complexes.
- McQuaid, M. J.,Morris, K.,Gole, J. L.
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p. 5280 - 5285
(2007/10/02)
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- Reactions of Atomic Scandium, Titanium, and Vanadium with Molecular Water at 15 K
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Scandium, titanium, and vanadium metal atoms were cocondensed with water molecules in an argon matreix at 15 K.The atomic metals were observed to insert spontaneously into the OH bond of water to form the HMOH molecule, which was found to be nonlinear in
- Kauffmann, J. W.,Hauge, R. H.,Margrave, J. L.
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p. 3547 - 3552
(2007/10/02)
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