Hydration of polar and nonpolar molecules at the surface of amorphous solid water
- Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)
On the basis of time-of-flight secondary ion mass spectrometry, properties of amorphous solid water above the glass transition temperature (136 K) and the hydration of polar (HCOOH,C{sub 3}H{sub 7}OH) and nonpolar (C{sub 6}H{sub 14},C{sub 6}F{sub 14}) molecules on the D{sub 2}O-ice surface have been investigated. No evidence was obtained for the irreversible transition of the amorphous solid water into the crystalline phase: the self-diffusion of water molecules occurs above 140 K irrespective of the preparation temperatures of the water-ice film ranging from 15 K to 165 K, whereas the morphology of the film changes drastically at 165 K due to the evolution of liquidlike water. It is also demonstrated that the change in conformation of the hydrated HCOOH molecule, as well as the occurrence of hydrophilic/hydrophobic hydration of the C{sub 3}H{sub 7}OH molecule, can be analyzed successfully from the temperature evolutions of the secondary-ion intensities. These polar molecules basically stay on the surface and tend to quench the morphological change of the water film due to the reduction of surface tension. The nonpolar C{sub 6}H{sub 14} and C{sub 6}F{sub 14} molecules readily dissolve in the D{sub 2}O layer below 100 K and dehydration of the incorporated molecules occurs at 165 K concomitantly with the evolution of the liquidlike water. It is thus concluded that the hydrophobic hydration of nonpolar molecules is intimately related to the properties of water films.
- OSTI ID:
- 20664934
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 16 Vol. 70; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AMORPHOUS STATE
FILMS
HEAVY WATER
HEXANE
HYDRATION
IONS
LAYERS
MASS SPECTRA
MASS SPECTROSCOPY
MOLECULES
SELF-DIFFUSION
SURFACE TENSION
SURFACES
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TIME-OF-FLIGHT METHOD
TRANSITION TEMPERATURE