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Poster De Conférence Année : 2006

Dynamics of ice Ih films upon methanol adsorption : quasielastic neutron scattering experiments and molecular dynamics simulations

Résumé

Quasielastic neutron scattering experiments and classical molecular dynamics simulations have been performed in similar conditions to investigate the effect of methanol adsorption on the dynamics of an ultra-thin ice Ih film (5 water layers thick) grown on a crystalline MgO(001) substrate. Experiments have been performed in the 220-270K temperature range and for a CH3OH monolayer coverage. At T=250K, about 20 % of the whole film is in the liquid state according to the measured molecular translational and rotational diffusion coefficients. At 270 K, our measurements show that this liquid fraction reaches almost 50 % of the whole film. Comparing these experimental results to those obtained for pure water/MgO(001) in the same temperature range indicates that the observed mobility is more probably due to methanol molecules rather than water molecules. These interpretations of the experimental data are supported by the results of the molecular dynamics simulations. Indeed, the calculated translational and rotational diffusion coefficients for the methanol/water/MgO system show that methanol molecules are much more mobile than water molecules between 250 and 270 K, and that the methanol layer behaves as a liquid-like layer adsorbed above rigid ice layers. Moreover, the comparison with results of simulations performed on the water/MgO system without methanol shows that the adsorbed methanol molecules strongly hinder the mobility of the underlying water molecules.
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hal-03691102 , version 1 (19-10-2022)

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  • HAL Id : hal-03691102 , version 1

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Stéphanie Lucas, Daniel Ferry, Benjamin Demirdjian, Jean Suzanne, Sylvain Picaud, et al.. Dynamics of ice Ih films upon methanol adsorption : quasielastic neutron scattering experiments and molecular dynamics simulations. 11th International Conference on the Physics and Chemistry of Ice (PCI-2006), Jul 2006, Bremerhaven, Germany. ⟨hal-03691102⟩
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