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G Mistura

Publications and source records attributed to G Mistura.

7 recordsLinked to original sources
PubMed2006

Structural depinning of Ne monolayers on Pb at T < 6/5 K.

We have studied the nanofriction of Ne monolayers with a quartz-crystal microbalance technique at temperatures below 6.5 K and in ultrahigh-vacuum conditions. Very homogeneous and smooth lead electrodes have been physically deposited on a quartz blank at 150 K and then annealed at room temperatures. With such a Pb-plated quartz-crystal microbalance, we have observed a pronounced depinning transition separating a low-coverage region, where the film is nearly locked to the oscillating electrode, from a high-coverage region characterized by slippage at the solid-fluid boundary. Such a behavior has been found to be very reproducible. These data are suggestive of a structural depinning of the solid Ne film when it becomes incommensurate with the lead substrate, in agreement with the results of an extensive molecular-dynamics study.

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PubMed2003

Crossover effects in the wetting of adsorbed films in linear wedges.

We have measured the growth of liquid Ar adsorbed on arrays of linear wedges structured in different ways. In the most regular patterns, a clear crossover from a planarlike to a geometry-dependent growth behavior is observed. This crossover is found to depend on the characteristic wedge size and its position, in the case of a regular pattern, agrees well with theoretical predictions. Near liquid-vapor bulk coexistence, the film mass is observed to diverge as a power law of the chemical potential difference from saturation with an exponent in very good agreement with the value of -2 expected for a linear wedge. This exponent is not affected by the opening angles of the wedges. The form of the next-to-leading order singular term in the asymptotic divergence of the mass has also been investigated. The experimentally determined value of the exponent is consistent with the expected theoretical result of -4/3.

Journal Article↗
PubMed2002

Complete wetting on a linear wedge.

We have measured the growth of liquid films of Ar adsorbed on well defined arrays of microscopic linear wedges sculpted on thin Si wafers and on a stainless steel disk. On these patterns, a clear cross-over from a planarlike to a geometry dependent growth behavior is observed. This crossover is found to depend on the characteristic wedge size. Near liquid-vapor bulk coexistence, the film mass is observed to diverge as a power law of the chemical potential difference from saturation with an exponent in very good agreement with the value of -2 expected for a linear wedge. This exponent is not affected by the opening angles of the wedges. All these findings are in accordance with a recent scaling theory.

Journal Article↗
PubMed2002

Depinning of atomically thin Kr films on gold.

We have employed the quartz-crystal microbalance technique to measure the sliding friction of krypton films physisorbed on gold. By slowly increasing the amplitude of the substrate oscillations, we have observed a sharp transition from a film locked to the substrate to a sliding one. This transition is characterized by hysteresis both in dissipation and inertial mass as the amplitude is decreased. Finally, the dependence of this transition on film coverage has been studied in some detail.

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