Studies of gas-phase clusters: the solvation of HNO3 in microscopic aqueous clusters

Kay, Bruce D.; Hermann, V.; Castleman, A. W.

doi:10.1016/0009-2614(81)85059-2

Cited by 76 publications

(78 citation statements)

References 12 publications

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“…[9][10][11] In bulk aqueous solutions and on ice, nitric acid can form hydrates with 1, 2 or 3 water molecules, depending on the concentration. 12-24 Such hydrates, as well as the HNO 3 dimer, have also been seen on solid surfaces during the hydrolysis of NO 2 at…”

Section: -8mentioning

confidence: 99%

“…Our simulations suggest the dimer is oriented such that the acidic proton of HNO 3 is pointing away from the gas phase and therefore unable to interact with the minimum number of water molecules needed to stabilize the contact ion pair. [9][10][11] Fig. 7 Infrared spectra of a SiO x /Ge ATR crystal coated with a C8= SAM in equilibrium with water vapor at 20-90% RH in the absence of HNO 3 .…”

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confidence: 99%

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Experimental and theoretical studies of the interaction of gas phase nitric acid and water with a self-assembled monolayer

Moussa

Stern

Raff

et al. 2013

Phys. Chem. Chem. Phys.

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Experimental and theoretical studies of the interaction of gas phase nitric acid and water with a self-assembled monolayer surface of a germanium infrared-transmitting attenuated total reflectance (ATR) crystal that was coated with a thin layer of silicon oxide (SiO x ). The SAM was exposed at 298 AE 2 K to dry HNO 3 in a flow of N 2 , followed by HNO 3 in humid N 2 at a controlled relative humidity (RH) between 20-90%. For comparison, similar studies were carried out using a similar crystal without the SAM coating. Changes in the surface were followed using Fourier transform infared spectroscopy (FTIR). In the case of the SAMcoated crystal, molecular HNO 3 and smaller amounts of NO 3 À ions were observed on the surface upon exposure to dry HNO 3 . Addition of water vapor led to less molecular HNO 3 and more H 3 O + and NO 3 À complexed to water, but surprisingly, molecular HNO 3 was still evident in the spectra up to 70% RH.This suggests that part of the HNO 3 observed was initially trapped in pockets within the SAM and shielded from water vapor. After increasing the RH to 90% and then exposing the film to a flow of dry N 2 , molecular nitric acid was regenerated, as expected from recombination of protons and nitrate ions as water evaporated. The nitric acid ultimately evaporated from the film. On the other hand, exposure of the SAM to HNO 3 and H 2 O simultaneously gave only hydronium and nitrate ions. Molecular dynamics simulations of defective SAMs in the presence of HNO 3 and water predict that nitric acid intercalates in defects as a complex with a single water molecule that is protected by alkyl chains from interacting with additional water molecules. These studies are consistent with the recently proposed hydrophobic nature of HNO 3 . Under atmospheric conditions, if HNO 3 is formed in organic layers on surfaces in the boundary layer, e.g. through NO 3 or N 2 O 5 reactions, it may exist to a significant extent in its molecular form rather than fully dissociated to nitrate ions. IntroductionNitric acid is considered to be the end-product of oxidation of oxides of nitrogen in the atmosphere. 1 This acid reacts with ammonia and amines to form solid or aqueous phase nitrate particles, and can also be taken up into other types of atmospheric particles. Removal of gaseous HNO 3 and particulate nitrates takes place primarily through wet and dry deposition, in what were once considered to be terminal removal processes. However, there are now a number of laboratory and field studies that suggest that nitric acid can be converted back into gaseous oxides of nitrogen such as NO, NO 2 and HONO. 2-8Nitric acid is a strong acid, but it requires a cluster of at least four water molecules to dissociate in the gas phase. [9][10][11] In bulk aqueous solutions and on ice, nitric acid can form hydrates with 1, 2 or 3 water molecules, depending on the concentration. 12-24 Such hydrates, as well as the HNO 3 dimer, have also been seen on solid surfaces during the hydrolysis of NO 2 at

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Section: -8mentioning

confidence: 99%

mentioning

confidence: 99%

Experimental and theoretical studies of the interaction of gas phase nitric acid and water with a self-assembled monolayer

Moussa

Stern

Raff

et al. 2013

Phys. Chem. Chem. Phys.

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“…Furthermore, HNO 3 has a strong affinity to ice, 19 where it rapidly dissociates. [20][21][22] To experimentally resolve these issues, we studied the reaction of HNO 3 with (H 2 O) n (n = 35-65) by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. The measurements are complemented with ab initio molecular dynamics simulations.…”

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confidence: 99%

Communication: Charge transfer dominates over proton transfer in the reaction of nitric acid with gas-phase hydrated electrons

Lengyel

Med

Slavı́ček

et al. 2017

The Journal of Chemical Physics

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The reaction of HNO3 with hydrated electrons (H2O)n− (n = 35–65) in the gas phase was studied using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and ab initio molecular dynamics simulations. Kinetic analysis of the experimental data shows that OH−(H2O)m is formed primarily via a reaction of the hydrated electron with HNO3 inside the cluster, while proton transfer is not observed and NO3−(H2O)m is just a secondary product. The reaction enthalpy was determined using nanocalorimetry, revealing a quite exothermic charge transfer with −241 ± 69 kJ mol−1. Ab initio molecular dynamics simulations indicate that proton transfer is an allowed reaction pathway, but the overall thermochemistry favors charge transfer.

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“…This is consistent with gas-phase studies of complexes of nitric acid with water, where ionization of the acid occurs when there are four or more water molecules in the cluster with one nitric acid molecule. [58][59][60] A decrease in the rate constant with increasing RH would also result if molecular HNO 3 is the reactant, while the dissociated ionic form, whose concentration increases with more water on the surface, is unreactive. Fig.…”

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HONO decomposition on borosilicate glass surfaces: implications for environmental chamber studies and field experiments

Syomin

Finlayson-Pitts

2003

Phys. Chem. Chem. Phys.

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Nitrous acid (HONO) is the major source of OH in polluted urban atmospheres, so an understanding of its formation and loss processes both in urban atmospheres and in laboratory systems is important. Earlier studies over a limited range of conditions showed that HONO is taken up and undergoes reaction on surfaces. We report here a comprehensive set of studies of the decay of HONO and the formation of gas phase products over a range of initial HONO concentrations (0.1-11 ppm) at 1 atm pressure in N 2 at 296 K and 0, 20 and 50% relative humidity (RH), respectively. The loss of HONO and increase in gas phase products were measured over time using long path FTIR spectroscopy. Studies were carried out in an unconditioned borosilicate glass cell and in the same cell after pretreatment with dry gaseous nitric acid. In the HNO 3 -conditioned cell, the loss of HONO was first order at all values of relative humidity (RH), and NO 2 was the only significant gas phase product. For the unconditioned cell, the reaction order increased from first order at 0% RH to second order at 50% RH. The gas phase products at 0% RH were equal amounts of NO and NO 2 . The yield of NO increased to > 90% at 50% RH while the yield of NO 2 decreased to 10%. For both the unconditioned and the HNO 3 -treated cell, the rate of loss of HONO decreased with increasing RH. These results suggest that there is a competition between water, HONO and HNO 3 for surface sites. Displacement of HONO from the cell walls by water was observed in separate experiments. Possible mechanisms, and the implications for HONO formation in environmental chambers and in air, are discussed.

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Studies of gas-phase clusters: the solvation of HNO3 in microscopic aqueous clusters

Cited by 76 publications

References 12 publications

Experimental and theoretical studies of the interaction of gas phase nitric acid and water with a self-assembled monolayer

Experimental and theoretical studies of the interaction of gas phase nitric acid and water with a self-assembled monolayer

Communication: Charge transfer dominates over proton transfer in the reaction of nitric acid with gas-phase hydrated electrons

HONO decomposition on borosilicate glass surfaces: implications for environmental chamber studies and field experiments

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