Isotopic exchange reactions in nitrogen oxides

Sharma, H. D.; Jervis, Rhodri; Wong, Kwok-Ming

doi:10.1021/j100699a044

Cited by 42 publications

(39 citation statements)

References 3 publications

(4 reference statements)

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“…20,42 In short, a monomode laser beam excites the NO 2 molecules in the cold region of a supersonic jet expansion. We have been unable to isolate pure asymmetric isotopologues because of the scrambling of oxygen atoms in gas-phase NO 2 via the transient formation of the N 2 O 4 dimers, 43 which produces a statistical mixture of symmetric and asymmetric isotopologues. Two critical parameters for the results presented here are the S / N ratio ͑which is higher than 10 +3 for the 16 O 14 N 16 O isotopologue͒ and the spectral resolution.…”

Section: Methodsmentioning

confidence: 99%

Comparison of rovibronic density of asymmetric versus symmetric NO2 isotopologues at dissociation threshold: Broken symmetry effects

Jost

Michalski

Thiemens

2005

The Journal of Chemical Physics

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We have measured the rovibronic densities of four symmetric (C2v) and two asymmetric (Cs) isotopologues of nitrogen dioxide just below their photodissociation threshold. At dissociation threshold and under jet conditions the laser-induced fluorescence abruptly disappears because the dissociation into NO(2pi(1/2)) + O(3P2) is much faster than the radiative decay. As a consequence, in a narrow energy range below D0, the highest bound rovibronic energy levels of J=1/2 and J=3/2 can be observed and sorted. A statistical analysis of the corresponding rovibronic density, energy spacing, and rovibronic transition intensities has been made. The observed intensity distributions are in agreement with the Porter-Thomas distribution. This distribution allows one to estimate the number of missing levels, and therefore to determine and compare the rovibronic and the vibronic densities. The four symmetric NO2 isotopologues, 16O14N16O, 18O14N18O, 16O15N16O, and 18O15N18O, have, respectively, a sum of J=1/2 and J=3/2 rovibronic densities of 18+/-0.8, 18.3+/-1.4, 18.4+/-2.7, and 19.8+/-3.5 cm(-1), while for the two asymmetric isotopologues, 18O14N16O and 18O15N16O, the corresponding densities are 20.9+/-4.5 and 23.6+/-5.6 cm(-1). The corresponding vibronic densities are in agreement only if we include both the merging of symmetry species (from those of C2v to those of Cs) and the contribution of the long-range tail(s) of the potential-energy surface along the dissociation coordinate. The effects of isotopic substitution on dissociation rates and the possible relation to mass-independent isotopic fractionation are discussed.

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Section: Methodsmentioning

confidence: 99%

Comparison of rovibronic density of asymmetric versus symmetric NO2 isotopologues at dissociation threshold: Broken symmetry effects

Jost

Michalski

Thiemens

2005

The Journal of Chemical Physics

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“…[40,41] Weakly bound (NO 2 ) 2 radical pairs probably play a crucial role also in the sym-N 2 O 4 -trans-ONONO 2 isomerisation, for which computational attempts to find a lowenergy pathway failed, [41,[59][60][61] or in the rapid gas-phase isotopic exchange reactions of isotopically labelled NO 2 [Eq. (5)]: [62] …”

Section: à1 ð1þmentioning

confidence: 99%

Intermediates Involved in the Oxidation of Nitrogen Monoxide: Photochemistry of the cis‐N₂O₂⋅O₂ complex and of sym‐N₂O₄ in Solid Ne Matrices

Beckers

Zeng

Willner

2010

Chemistry A European J

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Pure sym-N(2)O(4) isolated in solid Ne was obtained by passing cold neon gas over solid N(2)O(4) at -115 degrees C and quenching the resulting gaseous mixture at 6.3 K. Filtered UV irradiation (260-400 nm) converts sym-N(2)O(4) into trans-ONONO(2), a weakly interacting (NO(2))(2) radical pair, and traces of the cis-N(2)O(2)O(2) complex. Besides the weakly bound ONO(2) complex, cis-N(2)O(2)O(2) was also obtained by co-deposition of NO and O(2) in solid Ne at 6.3 K, and both complexes were characterised by their matrix IR spectra. Concomitantly formed cis-N(2)O(2) dissociated on exposure to filtered IR irradiation (400-8000 cm(-1)), and the cis-N(2)O(2)O(2) complex rearranged to sym-N(2)O(4) and trans-ONONO(2). Experiments using (18)O(2) in place of (16)O(2) revealed a non-concerted conversion of cis-N(2)O(2)O(2) into these species, and gave access to four selectively di-(18)O-substituted trans-ONONO(2) isotopomers. No isotopic scrambling occurred. The IR spectra of sym-N(2)O(4) and of trans-ONONO(2) in solid Ne were recorded. IR fundamentals of trans-ONONO(2) were assigned based on experimental (16/18)O isotopic shifts and guided by DFT calculations. Previously reported contradictory measurements on cis- and trans-ONONO(2) are discussed. Dinitroso peroxide, ONOONO, a proposed intermediate in the IR photoinduced rearrangement of cis-N(2)O(2)O(2) to the various N(2)O(4) species, was not detected. Its absence in the photolysis products indicates a low barrier (

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“…This dissolved calcium will be hereafter referred to as Ca, which exists especially close to the cathode (5,6). When TiCl 4 gas is injected to Ca, the metallic Ti is produced as, 2 Ca (in CaCl 2 ) + TiCl 4 (gas) = Ti (solid) + 2 CaCl 2 (liquid) [3] Eq. [3] occurs at the interface between the liquid and the gaseous phase as illustrated in Fig.1(a), and the metallic powder is formed as the product.…”

Section: Concept Of Proposalmentioning

confidence: 99%

“…When TiCl 4 gas is injected to Ca, the metallic Ti is produced as, 2 Ca (in CaCl 2 ) + TiCl 4 (gas) = Ti (solid) + 2 CaCl 2 (liquid) [3] Eq. [3] occurs at the interface between the liquid and the gaseous phase as illustrated in Fig.1(a), and the metallic powder is formed as the product. This powder formation is desirable for the continuous operation, and Ca neither reacts with Ti nor dissolves in Ti as the solid solution.…”

Section: Concept Of Proposalmentioning

confidence: 99%

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Calciothermic Reduction of TiCl4 Gas during the Electrolysis of CaCl2 Melt

Suzuki

Naitô

2009

ECS Trans.

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The calciothermic reduction of TiCl4 gas was studied firstly by using Ca-CaCl2 melt, to whose surface the gas was blown. The fine Ti particles settled down in the crucible, when the concentration of dissolved Ca was > 2 mol% at 1173 K. When < 2mol%Ca, a part of TiCl4 gas was dissolved probably as TiCl3 or TiCl2 into the CaCl2 melt, and it precipitated as the lower Ti oxides. When TiCl4 gas was blown to the molten CaCl2, which was electrochemically decomposed into Cl2 gas at the carbon anode and Ca at the Ti cathode, TiCl4 gas was reduced to the dendritic Ti on the cathode surface. Because the electrolyzed Ca reacted preferentially with the oxide crucibles, most of the oxygen ions combined with Ti(II) and Ti(III), and they formed TiO and Ti2O3

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Isotopic exchange reactions in nitrogen oxides

Cited by 42 publications

References 3 publications

Comparison of rovibronic density of asymmetric versus symmetric NO2 isotopologues at dissociation threshold: Broken symmetry effects

Comparison of rovibronic density of asymmetric versus symmetric NO2 isotopologues at dissociation threshold: Broken symmetry effects

Intermediates Involved in the Oxidation of Nitrogen Monoxide: Photochemistry of the cis‐N₂O₂⋅O₂ complex and of sym‐N₂O₄ in Solid Ne Matrices

Calciothermic Reduction of TiCl4 Gas during the Electrolysis of CaCl2 Melt

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Isotopic exchange reactions in nitrogen oxides

Cited by 42 publications

References 3 publications

Comparison of rovibronic density of asymmetric versus symmetric NO2 isotopologues at dissociation threshold: Broken symmetry effects

Comparison of rovibronic density of asymmetric versus symmetric NO2 isotopologues at dissociation threshold: Broken symmetry effects

Intermediates Involved in the Oxidation of Nitrogen Monoxide: Photochemistry of the cis‐N2O2⋅O2 complex and of sym‐N2O4 in Solid Ne Matrices

Calciothermic Reduction of TiCl4 Gas during the Electrolysis of CaCl2 Melt

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Intermediates Involved in the Oxidation of Nitrogen Monoxide: Photochemistry of the cis‐N₂O₂⋅O₂ complex and of sym‐N₂O₄ in Solid Ne Matrices