Adsorption of fluoroform CHF3 on ice Ih(0001): Structure and vibrations

Graham, Andrew; Menzel, A.; Toennies, J. P.

doi:10.1063/1.479301

Cited by 26 publications

(30 citation statements)

References 14 publications

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“…[13] For hydrofluorocarbon molecules (CH 4 , CH 3 F, CH 2 F 2 , and CHF 3 ), the length of the hydrogen bond between the fluorine carbon and the H 2 O molecule (CÀH···O) decreases and the C À H···O interaction energy increases with the number of fluorine (F) atoms in the molecules, according to theoretical calculations. [14] The CHF 3 molecule most likely orders the ice surface because of CÀH···O interaction between H 2 O molecules on the ice Ih(001) surface, [15] whereas for CH 4 and CF 4 the interactions with H 2 O molecules are weak. Therefore, the experimental result for CH 3 F hydrate suggests that relatively weak interactions (weaker than those of CH 2 F 2 and CH 3 F in this series) cause the self-preservation phenomenon because the interaction energy with H 2 O molecules should reflect the thermal adsorption of molecules on ice surfaces.…”

Section: Methodsmentioning

confidence: 99%

Dissociation Behavior of Clathrate Hydrates to Ice and Dependence on Guest Molecules

2008

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Section: Methodsmentioning

confidence: 99%

Dissociation Behavior of Clathrate Hydrates to Ice and Dependence on Guest Molecules

2008

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“…Another candidate for blocking the shafts is the similar molecule CHF 3 : helium scattering measurements suggest that CHF 3 is partly embedded into the ice surface, making it less corrugated. 65 If the penetration channel is indeed blocked when the ice surface is covered by a monolayer of molecules like CHF 3 or CH 4 , we would expect the the sticking probability ͑i.e., the adsorption probability͒ to show a monotonic decay with E i ͑Fig. 1͒.…”

Section: A Dependence Of the Sticking Probability On E I And Imentioning

confidence: 99%

Sticking of HCl to ice at hyperthermal energies: Dependence on incidence energy, incidence angle, and surface temperature

Al-Halabi

Kleyn

Kroes

2001

The Journal of Chemical Physics

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Articles you may be interested inElectron hole pair mediated vibrational excitation in CO scattering from Au(111): Incidence energy and surface temperature dependenceWe present calculations on the sticking of hyperthermal HCl to the basal plane ͑0001͒ face of ice I h at normal and off-normal incidence. The dependence of the sticking probability on the incidence energy (E i ), the angle of incidence ( i ), and the surface temperature (T s ) is discussed. Two sticking mechanisms are observed. For i р30°, penetration of the ͑0001͒ face is possible at an energy of about 100 kJ/mol, which is an order of magnitude lower than energies for which the penetration of metallic or covalently bonded crystals by atoms becomes possible. This possibility is due to the open structure of single-crystalline ice I h , in which the water molecules are arranged in superimposed hexagons, forming shafts running perpendicular to the ice surface. The penetration mechanism is operative for the entire range of T s studied ͑110-190 K͒. The second sticking mechanism, i.e., adsorption, occurs for all E i , i , and T i . For i Ͻ45°, the adsorption probability increases with i as would be expected, because the normal component of E i that needs to be transferred to the surface for sticking to occur scales with cos 2 i . However, for i у45°, the adsorption probability decreases with i . The energy transfer from HCl to the ice surface and the energy dissipation within the surface are found to be fast and efficient at normal incidence.

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“…Consequently, in experiments where CO is adsorbed to the ethylene oxide-ice system, the 2152 cm −1 band is never observed (Devlin 1992). Conversely, molecular dynamics simulations for crystalline ice show that CF 4 resides at the center of the surface hexagonal rings (similar to CHF 3 Graham et al 1999), blocking the water shafts and leaving only the dangling OH sites accessible (Buch et al 1996). In that case, the 2152 cm −1 band is seen first experimentally at low CO exposures, and its infrared signal is more intense than that of the 2139 cm −1 band, in contrast to the case of CO adsorption on a clean ice surface (Devlin 1992;Martin et al 2002b).…”

Section: Co-h 2 O Infrared Spectroscopymentioning

confidence: 99%

“…These molecules all bind more strongly to the ice than CO, so that the available adsorbing sites can be selected prior to CO adsorption (Devlin 1992;Graham et al 1999). For example, if ethylene oxide is pre-adsorbed to the ice surface, it forms a hydrogen bond with a "dangling OH" group, thereby blocking the adsorbing sites that correspond to the 2152 cm −1 band (Devlin 1992).…”

Section: Co-h 2 O Infrared Spectroscopymentioning

confidence: 99%

Adsorption of CO on amorphous water-ice surfaces

Al-Halabi

Fraser

Kroes

et al. 2004

A&A

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Abstract. We present the results of classical trajectory calculations of the adsorption of thermal CO on the surface of compact amorphous water ice, with a view to understanding the processes governing the growth and destruction of icy mantles on dust grains in the interstellar medium and interpreting solid CO infrared spectra. The calculations are performed at normal incidence, for E i = 0.01 eV (116 K) and surface temperature T s = 90 K. The calculations predict high adsorption probabilities (∼1), with the adsorbed CO molecules having potential energies ranging from −0.15 to −0.04 eV with an average energy of −0.094 eV. In all the adsorbing trajectories, CO sits on top of the surface. No case of CO diffusion inside the ice or into a surface valley with restricted access was seen. Geometry minimizations suggest that the maximum potential energy of adsorbed CO (−0.155 eV) occurs when CO interacts with a "dangling OH" group, associated with the 2152 cm −1 band seen in laboratory solid-state CO spectra. We show that relatively few "dangling OH" groups are present on the amorphous ice surface, potentially explaining the absence of this feature in astronomical spectra. CO also interacts with "bonded OH" groups, which we associate with the 2139 cm −1 infrared feature of solid CO. Our results for CO adsorption on amorphous ice are compared with those previously obtained for CO adsorption to crystalline ice. The implications of the spectroscopic assignments are discussed in terms of the solid-CO infrared spectra observed in interstellar regions. Using the Frenkel model, the lifetime τ for which CO may remain adsorbed at the surface is calculated. At temperatures relevant to the interstellar medium, i.e. 10 K, it is longer than the age of the universe, but decreases dramatically with increasing T s , such that at T s = 90 K, τ = 300 ns. The pre-exponential factor τ ν used in the Frenkel model is found to be 0.95 ± 0.02 ps. These data are compared to recent experimental results. The astrophysical implications of these calculations are discussed, with particular reference to the CO binding sites identified on amorphous ice surfaces, their adsorption energies, probabilities and lifetimes.

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Adsorption of fluoroform CHF3 on ice Ih(0001): Structure and vibrations

Cited by 26 publications

References 14 publications

Dissociation Behavior of Clathrate Hydrates to Ice and Dependence on Guest Molecules

Dissociation Behavior of Clathrate Hydrates to Ice and Dependence on Guest Molecules

Sticking of HCl to ice at hyperthermal energies: Dependence on incidence energy, incidence angle, and surface temperature

Adsorption of CO on amorphous water-ice surfaces

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