Substrate dependent sublimation kinetics of mesoscopic ice films

Löfgren, Patrik; Ahlström, Peter; Chakarov, Dinko; Lausmaa, Jukka; Kasemo, Bengt Herbert

doi:10.1016/s0039-6028(96)00944-2

Cited by 120 publications

(149 citation statements)

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“…Multilayer water desorption is independent of the substrate [12] and starts at $140 K [13]. This is exactly what we observe for the single desorption peak visible on D=Ptð533Þ: from the lowest coverages onwards we observe desorption at 140 K. The peak shows typical characteristics of zero order desorption kinetics.…”

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confidence: 82%

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Tuning Hydrophobicity of Platinum by Small Changes in Surface Morphology

Niet

Dunnen²,

Koper³

et al. 2011

Phys. Rev. Lett.

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Stepped platinum surfaces can become hydrophobic when they are hydrogenated. Even though the Pt(533) and Pt(553) surfaces have similar geometries, the hydrophobicity on the deuterated surface is surprisingly different: on Pt(533) the surface is hydrophobic with water clustering at steps, whereas the entire surface is wet on Pt(553). DOI: 10.1103/PhysRevLett.107.146103 PACS numbers: 68.08.Bc, 68.43.Hn, 82.45.Jn, 82.65.+r Groups of water molecules at an interface have the choice between interacting mostly with the substrate or with each other. This competition lies at the heart of a large variety of phenomena with wetting behavior of surfaces likely being the most well-known example. Contact angle studies date at least as far back as Thomas Young's work from the start of the 19th century [1]. Other important areas where such competition governs physical behavior are, e.g., protein folding and micelle formation [2].For solid surfaces, hydrophilic vs hydrophobic behavior appears difficult to predict. A recent study of water interacting with carbon nanotubes shows that in such confined spaces small changes in temperature may cause a switch between hydrophilic and hydrophobic interaction [3]. Also, minute details of the substrate appear to be of great relevance. A single molecular layer of amorphous solid water is hydrophilic [4], whereas the same layer of crystalline ice is hydrophobic [5].In this Letter, we show that a small change at the atomic level in substrate morphology without changing chemical identity or confinement size may also affect how water molecules adsorb to a surface. A switch from hydrophobic to hydrophilic behavior is not only apparent from drastic changes in H 2 O's desorption characteristics, but also in the chemical reactivity toward H-D exchange at well-ordered platinum surfaces. Our results impact on general thinking on long-range ordering of water molecules at interfaces and pose opportunities in tailoring chemistry occurring on nanoparticles as used in, e.g., heterogeneous catalysis and electrochemistry.As a substrate, we use single crystalline platinum discs, cut and polished to expose either the (533) or (553) surface. Schematic representations of these surfaces for top and side views are shown in Fig. 1 with every circle representing a Pt atom. The only difference between these surfaces is the step type that separates the 4-atom wide (111) terraces. The (533) surface contains the steeper (100) step type, whereas the (553) surface has the more gently sloped (110) step type. The angles that the singleatom high steps make with the terraces are, respectively, 116.6 and 125.3 . Our platinum surfaces are cleaned and studied under ultrahigh vacuum (UHV) conditions. Details on experimental procedures can be found in the Supplemental Material [6]. Low energy electron diffraction (LEED) confirms the atomic ordering of the surface as depicted in Fig. 1.The cleaned platinum surfaces are first exposed to D 2 by background dosing until no more dissociation occurs. To minimize contamination by H, t...

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confidence: 82%

“…Also, the deflection at $158 K for H 2 O ! 0:42 ML is located at the exact temperature where crystallization from amorphous solid water (ASW) to crystalline ice is observed for 25 ML of ASW on Pt(111) [13,14]. The formation of ASW under these conditions was also concluded from the Reflection Absorption Infrared Spectra we published earlier for this system [9].…”

supporting

confidence: 58%

Tuning Hydrophobicity of Platinum by Small Changes in Surface Morphology

Niet

Dunnen²,

Koper³

et al. 2011

Phys. Rev. Lett.

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“…A temperature of 142 K was chosen in accordance with previous isothermal TPD studies of water on HOPG. 12,14,15 Figure 5A shows an isothermal TPD spectrum recorded following a 40 langmuir exposure of water on HOPG. The spectrum is divided into three regions, labeled A, B, and C. Initially there is an increase in the desorption rate as desorption of the adlayer takes place during both the initial temperature ramp and with the sample held at 142 K. The desorption rate then rapidly decreases.…”

Section: Resultsmentioning

confidence: 99%

“…In this region, islands of water ice alternate with bare areas of the HOPG surface. 14,15 Sublimation of the ice causes a monotonic decrease in island size and effective island surface area. This leads to the monotonic decrease in desorption rate observed in region C. Note that region B will only be observed if the water ice film is sufficiently thick for multilayers to form.…”

Section: Resultsmentioning

confidence: 99%

Reflection Absorption Infrared Spectroscopy and Temperature-Programmed Desorption Studies of the Adsorption and Desorption of Amorphous and Crystalline Water on a Graphite Surface

2005

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Reflection absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) have been used to perform a detailed investigation of the adsorption of water on highly oriented pyrolytic graphite (HOPG) at 90 K. RAIRS shows that water is physisorbed on HOPG at all coverages, as expected. Experiments at higher surface temperatures show marked changes in the O-H stretching region of the spectrum which can be assigned to the observation of the amorphous to crystalline ice phase transition. The infrared signature of both phases of solid water has been determined on HOPG and can be used to identify the phase of the ice. TPD spectra show the desorption of multilayers of crystalline ice. At high exposures a small bump appears in the TPD spectrum, on the low temperature side of the main peak, which is attributed to the amorphous to crystalline phase transition. At very low exposures of water, it is possible to distinguish the desorption of water from two-and three-dimensional islands and hence to determine the growth mode of water on the HOPG surface. Isothermal TPD studies have also been performed and show that the desorption of water does not obey perfect zero-order kinetics. Desorption orders, derived directly from the TPD spectra, confirm this observation. Desorption energies and preexponential factors have also been determined for this adsorption system.

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“…The crystallization kinetics will provide information about the properties of supercooled liquid water. A variety of experimental techniques (including desorption, [16][17][18][19][20] physisorption, 11,21-24 infrared spectroscopy, 5,10,[25][26][27][28] and electron microcopy 12,29 ) have been used to study ASW crystallization. The majority of the above mentioned studies report that crystallization occurs via bulk nucleation although a few studies suggest that nucleation may start at the vacuum interface.…”

mentioning

confidence: 99%