A priori falloff analysis for OH + NO2

Matheu, David M.; Green, William

doi:10.1002/(sici)1097-4601(2000)32:4<245::aid-kin7>3.0.co;2-f

Cited by 30 publications

(9 citation statements)

References 40 publications

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“…Although Robertshaw and Smith 29 suggested already in 1982 that a second reaction channel existed that leads to the formation of ONOOH (favourable by 42 kJ mol −1 , Table 1), physical detection of ONOO − /ONOOH in the gas phase reaction proved elusive. 30 Anomalies in fall-off analyses of the gas-phase reaction at high pressure lent support to the existence of a second pathway for the reaction, 31 and theoretical treatment of the disappearance of HO˙in the presence of NO 2˙i ndicated that both ONOOH and HNO 3 contribute to the overall rate law. 32 Results from oxygen isotope 33 and reaction modulation Fourier transform infrared spectroscopy experiments 34 failed to directly demonstrate formation of ONOOH, but supported the likelihood of a second reaction path.…”

Section: Reinhard Kissnermentioning

confidence: 99%

Peroxynitrous acid: controversy and consensus surrounding an enigmatic oxidant

et al. 2012

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The isomerisation of ONOOH to NO(3)(-) and H(+), some oxidations and all hydroxylations and nitrations of aromatic compounds are first-order in ONOOH and zero-order in the compounds that are modified. These reactions are widely believed to proceed via homolysis of ONOOH into HO˙ and NO(2)˙ to an extent of ca. 30%. We review the evidence pro and contra homolysis in studies that involve (1) thermochemical considerations, (2) isomerisation to NO(3)(-) and H(+), (3) decomposition to NO(2)(-) and O(2), (4) HO˙ scavenger studies, (5) deuterium isotope effects, (6) (18)O-scrambling studies, (7) electrochemistry, (8) CIDNP NMR, and (9) photolysis. Our conclusion is that homolysis may be involved to a minor extent of ca. 5%. The initiation of ONOOH isomerisation may be visualised as an out-of-plane vibration of the terminal HO-group relative to the nitrogen. At ONOO(-) concentrations exceeding 0.1 mM and near neutral pH, disproportionation to NO(2)(-) and O(2) occurs; such disproportionations are typical for peroxy acids. For oxidation and nitration of organic substrates, we favour a mechanism involving initial formation of an adduct between the compound to be oxidised or nitrated and ONOOH.

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Section: Reinhard Kissnermentioning

confidence: 99%

Peroxynitrous acid: controversy and consensus surrounding an enigmatic oxidant

et al. 2012

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“…4,5,18 In the most recent study, Golden, Barker, and Lohr 2 have published a thorough multiwell, multichannel master equation model of the OHϩNO 2 system. Their modeling is consistent with previous experimental results, but all such calculations still rely on experimental constraints and cannot predict the behavior of this reaction from first principles.…”

Section: Fig 1 Energy Level Diagram For the Ohϩnomentioning

confidence: 99%

“…The excitation is to the first overtone of the OH stretch vibration (2 1 ), and the resulting OH fragment is detected via LIF. This technique combines molecular selectivity with very high sensitivity: The more stable isomer of nitric acid, HONO 2 , will not dissociate at this energy, and the LIF method is sensitive to as few as 10 4 OH molecules/cm 3 .…”

Section: A Action Spectroscopymentioning

confidence: 99%

“…The rate constant of this reaction has been the topic of some controversy [1][2][3][4][5][6][7] because the high and low pressure rate constants could not be reconciled with a single termolecular rate expression. This discrepancy can be resolved by the inclusion of a second minor channel forming a more weakly bound isomer of nitric acid, peroxynitrous acid, or HOONO, as first predicted by Robertshaw and Smith: 8 OHϩNO 2 ϩM →HONO 2 ϩM ͑1a͒…”

Section: Introductionmentioning

confidence: 99%

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Cis-cis and trans-perp HOONO: Action spectroscopy and isomerization kinetics

Fry

Nizkorodov

Okumura

et al. 2004

The Journal of Chemical Physics

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The weakly bound HOONO product of the OHϩNO 2 ϩM reaction is studied using the vibrational predissociation that follows excitation of the first OH overtone (2 1 ). We observe formation of both cis-cis and trans-perp conformers of HOONO. The trans-perp HOONO 2 1 band is observed under thermal ͑223-238 K͒ conditions at 6971 cm Ϫ1 . We assign the previously published ͑warmer temperature͒ HOONO spectrum to the 2 1 band at 6365 cm Ϫ1 and 2 1 -containing combination bands of the cis-cis conformer of HOONO. The band shape of the trans-perp HOONO spectrum is in excellent agreement with the predicted rotational contour based on previous experimental and theoretical results, but the apparent origin of the cis-cis HOONO spectrum at 6365 cm Ϫ1 is featureless and significantly broader, suggesting more rapid intramolecular vibrational redistribution or predissociation in the latter isomer. The thermally less stable trans-perp HOONO isomerizes rapidly to cis-cis HOONO with an experimentally determined lifetime of 39 ms at 233 K at 13 hPa ͑in a buffer gas of predominantly Ar͒. The temperature dependence of the trans-perp HOONO lifetime in the range 223-238 K yields an isomerization barrier of 33Ϯ12 kJ/mol. New ab initio calculations of the structure and vibrational mode frequencies of the transition state perp-perp HOONO are performed using the coupled cluster singles and doubles with perturbative triples ͓CCSD͑T͔͒ model, using a correlation consistent polarized triple basis set ͑cc-pVTZ͒. The energetics of cis-cis, trans-perp, and perp-perp HOONO are also calculated at this level ͓CCSD͑T͒/ cc-pVTZ͔ and with a quadruple basis set using the structure determined at the triple basis set ͓CCSD͑T͒/cc-pVQZ//CCSD͑T͒/cc-pVTZ͔. These calculations predict that the anti form of perp-perp HOONO has an energy of ⌬E 0 ϭ42.4 kJ/mol above trans-perp HOONO, corresponding to an activation enthalpy of ⌬H 298 ‡0 ϭ41.1 kJ/mol. These results are in good agreement with statistical simulations based on a model developed by Golden, Barker, and Lohr. The simulated isomerization rates match the observed decay rates when modeled with a trans-perp to cis-cis HOONO isomerization barrier of 40.8 kJ/mol and a strong collision model. The quantum yield of cis-cis HOONO dissociation to OH and NO 2 is also calculated as a function of photon excitation energy in the range 3500-7500 cm Ϫ1 , assuming D 0 ϭ83 kJ/mol. The quantum yield is predicted to vary from 0.15 to 1 over the observed spectrum at 298 K, leading to band intensities in the action spectrum that are highly temperature dependent; however, the observed relative band strengths in the cis-cis HOONO spectrum do not change substantially with temperature over the range 193-273 K. Semiempirical calculations of the oscillator strengths for 2 1 (cis-cis HOONO) and 2 1 (trans-perp HOONO) are performed using ͑1͒ a one-dimensional anharmonic model and ͑2͒ a Morse oscillator model for the OH stretch, and ab initio dipole moment functions calculated using Becke, Lee, Yang, and Parr density functional theory ͑B3LYP͒,...

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“…Golden and Smith, 31 Matheu and Green, 33 and Troe 34 have modeled the pressure and temperature dependence of k 1 and k 2 . Since the submission of this paper, there has been a new set of master equation calculations by Golden, Barker, and Lohr.…”

Section: Introductionmentioning

confidence: 99%

Cavity Ringdown Spectroscopy of cis-cis HOONO and the HOONO/HONO₂ Branching Ratio in the Reaction OH + NO₂ + M

et al. 2003

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The termolecular association reaction OH + NO 2 + M was studied in a low-pressure discharge flow reactor, and both HONO 2 and HOONO products were detected by infrared cavity ringdown spectroscopy (IR-CRDS). The absorption spectrum of the fundamental ν 1 band of the cis-cis isomer of HOONO (pernitrous or peroxynitrous acid) was observed at 3306 cm -1 , in good agreement with matrix isolation studies and ab initio predictions. The rotational contour of this band was partially resolved at 1 cm -1 resolution and matched the profile predicted by ab initio calculations. The integrated absorbances of the ν 1 bands of the cis-cis HOONO and HONO 2 products were measured as a function of temperature and pressure. These were converted to product branching ratios by scaling the experimentally observed absorbances with ab initio integrated cross sections for HOONO and HONO 2 computed at the CCSD(T)/cc-pVTZ level. The product branching ratio for cis-cis HOONO to HONO 2 was 0.075 ( 0.020(2σ) at room temperature in a 20 Torr mixture of He/Ar/N 2 buffer gas. The largest contribution to the uncertainty is from the ab initio ratio of the absorption cross sections, computed in the double harmonic approximation, which is estimated to be accurate to within 20%. The branching ratio decreased slightly with temperature over the range 270 to 360 K at 20 Torr. Although transperp HOONO was not observed, its energy was computed at the CCSD(T)/cc-pVTZ level to be E 0 ) +3.4 kcal/mol relative to the cis-cis isomer. Statistical rate calculations showed that the conformers of HOONO should reach equilibrium on the time scale of this exeriment. These results suggested that essentially all isomers had converted to cis-cis HOONO; thus, the reported branching ratio is a lower bound for and may represent the entire HOONO yield.

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A priori falloff analysis for OH + NO2

Cited by 30 publications

References 40 publications

Peroxynitrous acid: controversy and consensus surrounding an enigmatic oxidant

Peroxynitrous acid: controversy and consensus surrounding an enigmatic oxidant

Cis-cis and trans-perp HOONO: Action spectroscopy and isomerization kinetics

Cavity Ringdown Spectroscopy of cis-cis HOONO and the HOONO/HONO₂ Branching Ratio in the Reaction OH + NO₂ + M

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A priori falloff analysis for OH + NO2

Cited by 30 publications

References 40 publications

Peroxynitrous acid: controversy and consensus surrounding an enigmatic oxidant

Peroxynitrous acid: controversy and consensus surrounding an enigmatic oxidant

Cis-cis and trans-perp HOONO: Action spectroscopy and isomerization kinetics

Cavity Ringdown Spectroscopy of cis-cis HOONO and the HOONO/HONO2 Branching Ratio in the Reaction OH + NO2 + M

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Cavity Ringdown Spectroscopy of cis-cis HOONO and the HOONO/HONO₂ Branching Ratio in the Reaction OH + NO₂ + M