Quantitative Measurements of Multilayer Physical Adsorption on Heterogeneous Surfaces from Nonlinear Light Scattering

Henson, B. F.; Wilson, Kevin R.; Robinson, Jeanne M.

doi:10.1103/physrevlett.79.1531

Cited by 4 publications

(3 citation statements)

References 12 publications

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“…With this probe the nucleation of bulk hydrate or melt phases could be directly monitored, again in situ. 61 It was thus possible to obtain a quantitative measurement of the equilibrium coverage by adsorbed HCl as a function of the HCl and H 2 O vapor pressures and substrate temperature. From the measured pressures, temperatures, and SHG intensity from the surface it was also possible to directly confirm all thermodynamic phase boundaries, both interfacial and bulk, once again in situ.…”

Section: Methodsmentioning

confidence: 99%

“…growth of hydrate phases at high HCl pressure. 61 The extremely high sensitivity of pressure to coverage at the end of adsorption ( f ϭϱ) is the classic indication of the saturation of the surface by monolayer limited uptake. We therefore use a model derived from Langmuir's isotherm, modified to include lateral interactions through the Bragg-Williams approximation.…”

Section: Two-state Model Of Adsorptionmentioning

confidence: 99%

“…2͑a͒-2͑d͒ are presented to illustrate our ability to directly characterize, in situ, the thermodynamic phase of the ice interface under the conditions of interest at and above 180 K. We have previously demonstrated this at lower temperatures in the HCl/H 2 O system. 61 We have used observations such as these in every experiment conducted in this work to characterize the thermodynamic state of the interface. In addition, the observation of melting of the submonolayer adsorbed phase at a temperature coincident with the bulk hexahydate melting point is very interesting.…”

Section: A Hydrate Nucleation and Meltingmentioning

confidence: 99%

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Experimental isotherms of HCl on H2O ice under stratospheric conditions: Connections between bulk and interfacial thermodynamics

Henson

Wilson

Robinson

et al. 2004

The Journal of Chemical Physics

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The adsorption of HCl on the surface of H(2)O ice has been measured at temperatures and pressures relevant to the upper troposphere and lower stratosphere. The measured HCl surface coverage is found to be at least 100 times lower than currently assumed in models of chlorine catalyzed ozone destruction in cold regions of the upper atmosphere. Measurements were conducted in a closed system by simultaneous application of surface spectroscopy and gas phase mass spectrometry to fully characterize vapor/solid equilibrium. Surface adsorption is clearly distinguished from bulk liquid or solid phases. From 180 to 200 K, submonolayer adsorption of HCl is well described by a Bragg-Williams modified Langmuir model which includes the dissociation of HCl into H(+) and Cl(-) ions. Furthermore, adsorption is consistent with two distinct states on the ice substrate, one in which the ions only weakly adsorb on separate sites, and another where the ions adsorb as an H(+)-Cl(-) pair on a single site with adsorption energy comparable to the bulk trihydrate. The number of substrate H(2)O molecules per adsorption site is also consistent with the stoichiometry of bulk hydrates under these conditions. The ionic states exist in equilibrium, and the total adsorption energy is a function of the relative population of both states. These observations and model provide a quantitative connection between the thermodynamics of the bulk and interfacial phases of HCl/H(2)O, and represent a consistent physicochemical model of the equilibrium system.

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Section: Methodsmentioning

confidence: 99%

Section: Two-state Model Of Adsorptionmentioning

confidence: 99%

Section: A Hydrate Nucleation and Meltingmentioning

confidence: 99%

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Experimental isotherms of HCl on H2O ice under stratospheric conditions: Connections between bulk and interfacial thermodynamics

Henson

Wilson

Robinson

et al. 2004

The Journal of Chemical Physics

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The structural diversity of hybrid qy-HMX crystals with constraint of 2D dopants and the resulted changes in thermal reactivity

Xue

Zhang

Huang

et al. 2020

Chemical Engineering Journal

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Thermodynamic model of quasiliquid formation on H2O ice: Comparison with experiment

Henson

Voss

Wilson

et al. 2005

The Journal of Chemical Physics

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We have developed a new thermodynamic theory of the quasiliquid layer, which has been shown to be effective in modeling the phenomenon in a number of molecular systems. Here we extend our analysis to H(2)O ice, which has obvious implications for environmental and atmospheric chemistry. In the model, the liquid layer exists in contact with an ice defined as a two-dimensional lattice of sites. The system free energy is defined by the bulk free energies of ice I(h) and liquid water and is minimized in the grand canonical ensemble. An additional configurational entropy term arises from the occupation of the lattice sites. Furthermore, the theory predicts that the layer thickness as a function of temperature depends only on the liquid activity. Two additional models are derived, where slightly different approximations are used to define the free energy. With these two models, we illustrate the connection between the quasiliquid phenomenon and multilayer adsorption and the possibility of a two-dimensional phase transition connecting a dilute low coverage phase of adsorbed H(2)O and the quasiliquid phase. The model predictions are in agreement with a subset of the total suite of experimental measurements of the liquid thickness on H(2)O ice as a function of temperature. The theory indicates that the quasiliquid layer is actually equivalent to normal liquid water, and we discuss the impact of such an identification. In particular, observations of the liquid layer to temperatures as low as 200 K indicate the possibility that the quasiliquid is, in fact, an example of deeply supercooled normal water. Finally, we briefly discuss the obvious extension of the pure liquid theory to a thermodynamic theory of interfacial solutions on ice in the environment.

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Quantitative Measurements of Multilayer Physical Adsorption on Heterogeneous Surfaces from Nonlinear Light Scattering

Cited by 4 publications

References 12 publications

Experimental isotherms of HCl on H2O ice under stratospheric conditions: Connections between bulk and interfacial thermodynamics

Experimental isotherms of HCl on H2O ice under stratospheric conditions: Connections between bulk and interfacial thermodynamics

The structural diversity of hybrid qy-HMX crystals with constraint of 2D dopants and the resulted changes in thermal reactivity

Thermodynamic model of quasiliquid formation on H2O ice: Comparison with experiment

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