New Insights in the Atmospheric HONO Formation: New Pathways for N2O4 Isomerization and NO2 Dimerization in the Presence of Water

Medeiros, Diogo de Jesus; Pimentel, André Silva

doi:10.1021/jp1123585

Cited by 48 publications

(64 citation statements)

References 21 publications

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“…It is currently believed that a major source of nocturnal HONO is the heterogeneous hydrolysis of NO 2 on humid surfaces (e.g., Finlayson-Pitts et al, 2003;Ramazan et al, 2006;de Jesus Medeiros and Pimentel, 2011). Using a 1D chemistry and transport model, Wong et al (2011) showed that this mechanism, together with an accurate description of vertical mixing, is able to successfully explain the nocturnal HONO observations in Houston.…”

Section: Heterogeneous Pathways For Atmospheric Hono Formationmentioning

confidence: 99%

Implementation and refinement of a surface model for heterogeneous HONO formation in a 3-D chemical transport model

Karamchandani

Emery

Yarwood

et al. 2015

Atmospheric Environment

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Section: Heterogeneous Pathways For Atmospheric Hono Formationmentioning

confidence: 99%

Implementation and refinement of a surface model for heterogeneous HONO formation in a 3-D chemical transport model

Karamchandani

Emery

Yarwood

et al. 2015

Atmospheric Environment

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“…Additionally, alternate mechanisms have arisen from AIMD simulations of the reaction with one to seven water molecules. 12 For the reaction of (NO + )(NO 3 − ) with water, a cluster size of (H 2 O) 4 was used based on previous work that established the role of the hydrogen-bonding network in promoting reaction of NO + with water. 16 A similar water configuration was identified solvating the cis-ONONO 2 and trans-ONONO 2 isomers of asym-N 2 O 4 [ Figure 1a,b].…”

Section: Clusters As Models For Reactions Onmentioning

confidence: 99%

Computational Studies of Atmospherically-Relevant Chemical Reactions in Water Clusters and on Liquid Water and Ice Surfaces

et al. 2015

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CONSPECTUS: Reactions on water and ice surfaces and in other aqueous media are ubiquitous in the atmosphere, but the microscopic mechanisms of most of these processes are as yet unknown. This Account examines recent progress in atomistic simulations of such reactions and the insights provided into mechanisms and interpretation of experiments. Illustrative examples are discussed. The main computational approaches employed are classical trajectory simulations using interaction potentials derived from quantum chemical methods. This comprises both ab initio molecular dynamics (AIMD) and semiempirical molecular dynamics (SEMD), the latter referring to semiempirical quantum chemical methods. Presented examples are as follows: (i) Reaction of the (NO(+))(NO3(-)) ion pair with a water cluster to produce the atmospherically important HONO and HNO3. The simulations show that a cluster with four water molecules describes the reaction. This provides a hydrogen-bonding network supporting the transition state. The reaction is triggered by thermal structural fluctuations, and ultrafast changes in atomic partial charges play a key role. This is an example where a reaction in a small cluster can provide a model for a corresponding bulk process. The results support the proposed mechanism for production of HONO by hydrolysis of NO2 (N2O4). (ii) The reactions of gaseous HCl with N2O4 and N2O5 on liquid water surfaces. Ionization of HCl at the water/air interface is followed by nucleophilic attack of Cl(-) on N2O4 or N2O5. Both reactions proceed by an SN2 mechanism. The products are ClNO and ClNO2, precursors of atmospheric atomic chlorine. Because this mechanism cannot result from a cluster too small for HCl ionization, an extended water film model was simulated. The results explain ClNO formation experiments. Predicted ClNO2 formation is less efficient. (iii) Ionization of acids at ice surfaces. No ionization is found on ideal crystalline surfaces, but the process is efficient on isolated defects where it involves formation of H3O(+)-acid anion contact ion pairs. This behavior is found in simulations of a model of the ice quasi-liquid layer corresponding to large defect concentrations in crystalline ice. The results are in accord with experiments. (iv) Ionization of acids on wet quartz. A monolayer of water on hydroxylated silica is ordered even at room temperature, but the surface lattice constant differs significantly from that of crystalline ice. The ionization processes of HCl and H2SO4 are of high yield and occur in a few picoseconds. The results are in accord with experimental spectroscopy. (v) Photochemical reactions on water and ice. These simulations require excited state quantum chemical methods. The electronic absorption spectrum of methyl hydroperoxide adsorbed on a large ice cluster is strongly blue-shifted relative to the isolated molecule. The measured and calculated adsorption band low-frequency tails are in agreement. A simple model of photodynamics assumes prompt electronic relaxation of the excited peroxide due t...

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“…2NO 2 (g)+H 2 O(l) → HONO(g)+H + (aq)+NO − 3 (aq) (R4) Yabushita et al (2009) andDe Jesus Medeiros andPimentel (2011) further investigated the mechanism with focus on the NO 2 uptake and the kinetics of the initial hydrolysis. The reaction rate constant of Reaction (R4) is difficult to determine in the field but can be estimated with the approach of Alicke et al (2002).…”

Section: Introductionmentioning

confidence: 99%

A comparison of HONO budgets for two measurement heights at a field station within the boreal forest in Finland

et al. 2015

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Abstract. Atmospheric concentrations of nitrous acid (HONO), one of the major precursors of the hydroxyl radical (OH) in the troposphere, significantly exceed the values predicted by the assumption of a photostationary state (PSS) during daytime. Therefore, additional sources of HONO were intensively investigated in the last decades. This study presents budget calculations of HONO based on simultaneous measurements of all relevant species, including HONO and OH at two different measurement heights, i.e. 1 m above the ground and about 2 to 3 m above the canopy (24 m above the ground), conducted in a boreal forest environment. We observed mean HONO concentrations of about 6.5 × 10 8 molecules cm −3 (26 ppt) during daytime, more than 20 times higher than expected from the PSS of 0.2 × 10 8 molecules cm −3 (1 ppt). To close the budgets at both heights, a strong additional source term during daytime is required. This unidentified source is at its maximum at noon (up to 1.1 × 10 6 molecules cm −3 s −1 , 160 ppt h −1 ) and in general up to 2.3 times stronger above the canopy than close to the ground. The insignificance of known gas phase reactions and other processes like dry deposition or advection compared to the photolytic decomposition of HONO at this measurement site was an ideal prerequisite to study possible correlations of this unknown term to proposed HONO sources. But neither the proposed emissions from soils nor the proposed photolysis of adsorbed HNO 3 contributed substantially to the unknown source. However, the unknown source was found to be perfectly correlated to the unbalanced photolytic loss of HONO.

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New Insights in the Atmospheric HONO Formation: New Pathways for N₂O₄ Isomerization and NO₂ Dimerization in the Presence of Water

Cited by 48 publications

References 21 publications

Implementation and refinement of a surface model for heterogeneous HONO formation in a 3-D chemical transport model

Implementation and refinement of a surface model for heterogeneous HONO formation in a 3-D chemical transport model

Computational Studies of Atmospherically-Relevant Chemical Reactions in Water Clusters and on Liquid Water and Ice Surfaces

A comparison of HONO budgets for two measurement heights at a field station within the boreal forest in Finland

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