Dynamics of collisions of hydroxyl radicals with fluorinated self-assembled monolayers

Troya, Diego

doi:10.1007/978-3-642-28445-8_9

Cited by 5 publications

(6 citation statements)

References 34 publications

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“…[28][29][30]33,35,44,46,52,56,81 The predominance of single-bounce, IS-type trajectories with some conversion of translational to rotational energy is also consistent with the QCT predictions of Troya on a fluorinated SAM surface, expected to be reasonable model for PFPE, at the somewhat higher collision energy of our earlier experiments. 44,45,82 The somewhat higher rotational temperature for squalene has also been seen by us previously, for which we have offered a potential explanation based on differential survival probabilities of hotter, less thermally accommodated molecules. 15,16 We return to this below in the context of our new measurements here of the collision-energy dependence of this survival.…”

Section: Table 2 Survival Probabilities Of Od From Each Liquid Surfacesupporting

confidence: 79%

Collision-Energy Dependence of the Uptake of Hydroxyl Radicals at Atmospherically Relevant Liquid Surfaces

et al. 2018

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A new experimental approach to the study of collisions of hydroxyl radicals with liquid surfaces is described, incorporating a molecular-beam source of OH (or, in practice, OD, for technical reasons) radicals. This allowed the collision-energy dependence of the scattering to be examined. The incident and scattered OD molecules were detected by laser-induced fluorescence. The representative branched, long-chain alkane, squalane (2,6,10,15,19,23-hexamethyltetracosane), and its partially unsaturated analogue, squalene (2,6,10,15,19,23-hexamethyl-2,6,10,14,18,22-tetracosahexaene), were compared with perfluoropolyether as an inert reference liquid. Dynamical aspects of the scattering necessary to quantify the OD survival probability, and hence its complement, the reactive sticking coefficient, were determined. Results were obtained at average laboratory-frame kinetic energies of 7.2 and 29.5 kJ mol −1 ; they are compared with previous independent measurements using a photolytic source of OH with an average kinetic energy of 54 kJ mol −1 . At lower collision energies, the survival probability is significantly lower on squalene than on squalane but increases significantly with collision energy. This is consistent with a negatively activated contribution to loss of hydroxyl through addition to double-bond sites at the squalene surface. In contrast, survival on squalane surface is found to be approximately independent of collision energy across the range examined. This is surprising because it does not reflect the positively activated behavior typical of gas-phase OH + alkane reactions. We suggest that this may be explained by a higher probability of trapping dynamics at lower collision energies, enhancing the probability of reaction following migration to more reactive sites. The results have implications for the modeling of OH uptake on atmospheric aerosol surfaces as a function of chemical composition and temperature.

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Section: Table 2 Survival Probabilities Of Od From Each Liquid Surfacesupporting

confidence: 79%

Collision-Energy Dependence of the Uptake of Hydroxyl Radicals at Atmospherically Relevant Liquid Surfaces

et al. 2018

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“…Product rotational distributions could be fitted to a single rotational temperature that was higher than the incident value, suggesting translational-to-rotational energy conversion in impulsive collisions at the surface. This result was supported by simulations of scattering from F-SAMs (77). Rotational temperatures and the component of translationally slower products that could be associated with a TD fraction were consistent with trends in surface stiffness.…”

Section: Nonreactive Gas-surface Interactionssupporting

confidence: 63%

Atomic and Molecular Collisions at Liquid Surfaces

Tesa-Serrate

Smoll

Minton

et al. 2016

Annu. Rev. Phys. Chem.

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The gas-liquid interface remains one of the least explored, but nevertheless most practically important, environments in which molecular collisions take place. These molecular-level processes underlie many bulk phenomena of fundamental and applied interest, spanning evaporation, respiration, multiphase catalysis, and atmospheric chemistry. We review here the research that has, during the past decade or so, been unraveling the molecular-level mechanisms of inelastic and reactive collisions at the gas-liquid interface. Armed with the knowledge that such collisions with the outer layers of the interfacial region can be unambiguously distinguished, we show that the scattering of gas-phase projectiles is a promising new tool for the interrogation of liquid surfaces with extreme surface sensitivity. Especially for reactive scattering, this method also offers absolute chemical selectivity for the groups that react to produce a specific observed product.

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“…Self-assembled monolayers (SAMs), and in particular alkanethiolate monolayers on noble metals, are model organic surface systems that offer tractable experimental control of structure and functionality. , Consequently, these organic surfaces have been the subject of a number of gas–surface reaction studies, including experimental investigations by the Morris, ,− McKendrick, , Minton, ,, and Sibener ,− groups and theoretical works by the Schatz, , Troya, − and Hase − groups. These studies have focused on scattering of gas-phase reagents, typically measuring or calculating angle-dependent kinetic energy distributions.…”

mentioning

confidence: 99%

Reactivity of Gas-Phase Radicals with Organic Surfaces

Lee

Kautz

Kandel

2013

J. Phys. Chem. Lett.

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In chemical reactions at the gas–surface interface, the heterogeneity in structure of reaction sites plays a critical role in determining surface reactivity. This Perspective describes reaction mechanisms in such systems and details the use of in situ scanning probe microscopy to investigate reactions of gas-phase radicals with self-assembled alkanethiolate monolayers on gold surfaces. For both atomic hydrogen and atomic chlorine reagents, the presence of defects in the alkanethiolate surface order has a substantial influence on what reactions can occur and the speed at which they do so. Data acquired from a series of images were modeled using kinetic Monte Carlo simulations, and a surface radical reaction model was developed to explain the observed evolution of surface structure as the reactions proceed.

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Dynamics of collisions of hydroxyl radicals with fluorinated self-assembled monolayers

Cited by 5 publications

References 34 publications

Collision-Energy Dependence of the Uptake of Hydroxyl Radicals at Atmospherically Relevant Liquid Surfaces

Collision-Energy Dependence of the Uptake of Hydroxyl Radicals at Atmospherically Relevant Liquid Surfaces

Atomic and Molecular Collisions at Liquid Surfaces

Reactivity of Gas-Phase Radicals with Organic Surfaces

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