Abstract
When water is adsorbed on Pt(111) above 135 K several different ice structures crystallize, depending on the thickness of the ice layer. At low coverage water forms extended islands of ice with a (√37×√37) R25° unit cell, which compresses as the monolayer saturates to form a (√39×√39) R16° structure. The √39 low-energy electron diffraction (LEED) pattern becomes more intense as the second layer grows, remaining bright for films up of 10-15 layers and then fading and disappearing for films more than ca. 40 layers thick. The ice multilayer consists of an ordered √39 wetting layer, on which ice grows as a crystalline film which progressively loses its registry to the wetting layer. Ice films more than ca. 50 layers thick develop a hexagonal LEED pattern, the entire film and wetting layer reorienting to form an incommensurate bulk ice. These changes are reflected in the vibrational spectra which show changes in line shape and intensity associated with the different ice structures. Thin amorphous solid water films crystallize to form the same phases observed during growth, implying that these structures are thermodynamically stable and not kinetic phases formed during growth. The change from a √39 registry to incommensurate bulk ice at ca. 50 layers is associated with a change in crystallization kinetics from nucleation at the Pt(111) interface in thin films to nucleation of incommensurate bulk ice in amorphous solid water films more than 50 layers thick.
| Language | English |
|---|---|
| Article number | 174701 |
| Journal | Journal of Chemical Physics |
| Volume | 123 |
| Issue number | 17 |
| DOIs | |
| Publication status | Published - 1 Nov 2005 |
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Keywords
- ice
- Pt(111)
- thin film structure
- crystal structure
- low-energy electron diffraction (LEED)
- thin films
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The structure and crystallization of thin water films on Pt(111). / Zimbitas, G.; Haq, S.; Hodgson, A.
In: Journal of Chemical Physics, Vol. 123, No. 17, 174701, 01.11.2005.Research output: Contribution to journal › Article
TY - JOUR
T1 - The structure and crystallization of thin water films on Pt(111)
AU - Zimbitas, G.
AU - Haq, S.
AU - Hodgson, A.
PY - 2005/11/1
Y1 - 2005/11/1
N2 - When water is adsorbed on Pt(111) above 135 K several different ice structures crystallize, depending on the thickness of the ice layer. At low coverage water forms extended islands of ice with a (√37×√37) R25° unit cell, which compresses as the monolayer saturates to form a (√39×√39) R16° structure. The √39 low-energy electron diffraction (LEED) pattern becomes more intense as the second layer grows, remaining bright for films up of 10-15 layers and then fading and disappearing for films more than ca. 40 layers thick. The ice multilayer consists of an ordered √39 wetting layer, on which ice grows as a crystalline film which progressively loses its registry to the wetting layer. Ice films more than ca. 50 layers thick develop a hexagonal LEED pattern, the entire film and wetting layer reorienting to form an incommensurate bulk ice. These changes are reflected in the vibrational spectra which show changes in line shape and intensity associated with the different ice structures. Thin amorphous solid water films crystallize to form the same phases observed during growth, implying that these structures are thermodynamically stable and not kinetic phases formed during growth. The change from a √39 registry to incommensurate bulk ice at ca. 50 layers is associated with a change in crystallization kinetics from nucleation at the Pt(111) interface in thin films to nucleation of incommensurate bulk ice in amorphous solid water films more than 50 layers thick.
AB - When water is adsorbed on Pt(111) above 135 K several different ice structures crystallize, depending on the thickness of the ice layer. At low coverage water forms extended islands of ice with a (√37×√37) R25° unit cell, which compresses as the monolayer saturates to form a (√39×√39) R16° structure. The √39 low-energy electron diffraction (LEED) pattern becomes more intense as the second layer grows, remaining bright for films up of 10-15 layers and then fading and disappearing for films more than ca. 40 layers thick. The ice multilayer consists of an ordered √39 wetting layer, on which ice grows as a crystalline film which progressively loses its registry to the wetting layer. Ice films more than ca. 50 layers thick develop a hexagonal LEED pattern, the entire film and wetting layer reorienting to form an incommensurate bulk ice. These changes are reflected in the vibrational spectra which show changes in line shape and intensity associated with the different ice structures. Thin amorphous solid water films crystallize to form the same phases observed during growth, implying that these structures are thermodynamically stable and not kinetic phases formed during growth. The change from a √39 registry to incommensurate bulk ice at ca. 50 layers is associated with a change in crystallization kinetics from nucleation at the Pt(111) interface in thin films to nucleation of incommensurate bulk ice in amorphous solid water films more than 50 layers thick.
KW - ice
KW - Pt(111)
KW - thin film structure
KW - crystal structure
KW - low-energy electron diffraction (LEED)
KW - thin films
UR - http://www.scopus.com/inward/record.url?scp=27644572571&partnerID=8YFLogxK
U2 - 10.1063/1.2060691
DO - 10.1063/1.2060691
M3 - Article
VL - 123
JO - Journal of Chemical Physics
T2 - Journal of Chemical Physics
JF - Journal of Chemical Physics
SN - 0021-9606
IS - 17
M1 - 174701
ER -