Temperature-dependent behaviour of capillary waves at Hg - vapour and Hg - HgO interfaces

Kolevzon, Vladimir; Pozdniakov, Georgij

doi:10.1088/0953-8984/9/32/005

Cited by 7 publications

(13 citation statements)

References 17 publications

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“…When a monolayer is present there is a strong increase in the capillary wave damping in comparison with that for the free surface of the subphase; this is our case as can be seen by an inspection of the half-widths of the spectra (see Figure ). Nevertheless, even under conditions of strong damping, the q -power of the capillary damping reported for a monolayer spread on a simple liquid are not far from the ideal value ( ∼ q 2 ), ,,, in contrast with the present results. Furthermore, some of our experimental values show q -dependences close to the one that will be expected for pure dilational waves (∼ q 4/3 ).…”

Section: Resultscontrasting

confidence: 99%

“…As can be observed, γ is always larger than γ d by ca. 6 mN/m, which is a signature of the presence of a monolayer in the whole temperature range. , At T f = 312.2 K there is a discontinuity in dγ d /d T , indicating the phase transition: this value agrees well with the value of T f obtained from the static results. It is worth mentioning that the constancy of γ d −γ, with the temperature is a first indication of an unexpected result: in effect, for a monolayer, the capillary wave frequency is essentially determined 30 by the values of γ and ε, thus our results indicate that the difference in dilational elasticity between the 2D liquid and the solid is small.…”

Section: Resultssupporting

confidence: 83%

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Viscoelastic Behavior of 1-Dodecanol Monolayers Undergoing a Liquid−Solid Phase Transition. A Surface Quasielastic Light Scattering Study

et al. 2000

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A surface quasielastic light scattering (SQELS) and electrocapillary wave (ECW) study of a monolayer of 1-dodecanol, obtained by placing a reservoir drop of the alcohol on top of a water surface, has been carried out as a function of temperature at different wavevectors. This monolayer goes through a liquid-solid phase transition at 312.1 K, more than 14 K above the freezing of bulk 1-dodecanol. The fit of the SQELS spectra gives the frequency, ωc, and the temporal damping, ∆ωc, of thermally induced capillary waves. In all the temperature range ωc follows Kelvin-like behavior (i.e., ωc ∼ q 3/2 ) leading to values of the apparent dynamic surface tension lower than the static ones. In addition the damping follows, ∆ωc ∼ q 1.2-1.4 very far from the expected ∼q 2 dispersion behavior. Both wave parameters show temperature trends compatible with the expected liquid-solid 2D phase transition at around 312 K. The expansion of the frequency range by using the ECW technique, shows that our experimental results cover the regions q e qR e q, where qR is the wavevector at which capillary-dilational resonance takes place. Within the classical elastohydrodynamic theory, our results can be accounted for if the dilational viscosity, κ, takes a negative sign. In these conditions mode mixing takes place for q g qR. Alternatively the experimental results can be quantitatively explained with κ ) 0 if an extra hydrodynamic coupling is included in the dispersion equation. From a physicochemical point of view this coupling may arise from the vicinity of the phase transition and/or molecular orientational effects promoted by the dilational wave. The small values of the dynamic elasticity, (ω), found in this work can be rationalized in terms of a monolayer-subsurface material transport, within the Lucassen-Van de Tempel model.

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Section: Resultscontrasting

confidence: 99%

Section: Resultssupporting

confidence: 83%

Viscoelastic Behavior of 1-Dodecanol Monolayers Undergoing a Liquid−Solid Phase Transition. A Surface Quasielastic Light Scattering Study

et al. 2000

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“…Optical measurements on Hg surfaces with varying degrees of cleanliness have found d␥/dT in the range of Ϫ0.7ϫ10 Ϫ3 to ϩ0.3ϫ10 Ϫ3 N/mK depending on the method of sample preparation. 22 The observation that oxide or contamination can produce d␥/dTϾ0 for Hg is notable, but this would cause a reduction of T with increasing T rather than the increase observed, and so cannot account for our results.…”

Section: R13 420mentioning

confidence: 66%

X-ray reflectivity study of temperature-dependent surface layering in liquid Hg

et al. 1998

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We report x-ray reflectivity measurements of liquid mercury between Ϫ36°C and ϩ25°C. The surface structure can be described by a layered density profile convolved with a thermal roughness T . The layering has a spacing of 2.72 Å and an exponential decay length of 5.0 Å. Surprisingly, T is found to increase considerably faster with temperature than the ͱT behavior predicted by capillary wave theory, in contrast with previous measurements on Ga and dielectric liquids. ͓S0163-1829͑98͒52144-3͔The effect of temperature on the surface structure of a liquid is quite different from that of a solid surface. In the liquid, thermal surface waves are excited at all wavelengths from the particle spacing to a long wavelength gravitational cutoff, and produce a surface roughness on the order of the particle spacing. For nonmetallic liquids, these capillary waves broaden the liquid-vapor interface, which is a monotonically decreasing density profile with a width of several Å. 1 Metallic liquids exhibit a more complex surface structure in which the atoms are stratified parallel to the liquid-vapor interface in layers that persist into the bulk for a few atomic diameters. This layering arises from the strongly densitydependent nonlocal interionic potential 2 and is unique to metallic liquids. Nevertheless, the effect of temperature is still expected to be principally in the form of capillary waves, which roughen the surface-normal profile and diminish the layering amplitude. X-ray reflectivity measurements have confirmed the existence of surface layering in liquid Hg, 3 Ga, 4 In, 5 and several alloys. 6,7 Models based on capillary waves as the only mechanism for surface roughening were found to describe the temperature-dependent layering of liquid Ga 8 as well as diffuse scattering measured from the liquid In surface. 5 In previous comparisons of the x-ray reflectivity of liquid Hg and Ga, 9 two important differences were identified. Although reflectivities for both metals exhibit quasi-Bragg peaks indicative of surface layering, the Hg data have a minimum at low-momentum transfer (q z Ϸ0.6 Å Ϫ1 ) not found in Ga ͑see Fig. 2 in Ref. 9͒. To describe this minimum, the model for the surface structure had to be more complex than that of Ga. One successful model incorporated a low density region persisting a few Å into the vapor side of the interface.This feature was taken to be intrinsic to Hg. In addition, the room-temperature layering peak appeared to be broader for Hg than for Ga, leading to the conclusion that in Hg, surface layering decayed over a much shorter length scale.Subsequent measurements yielded variations in this lowq z minimum, prompting us to address the possible effect of impurities at the surface. An important difference between experiments on Hg and Ga is that due to the low vapor pressure, Ga can be measured under ultra-high-vacuum ͑UHV͒ conditions and cleaned in situ by argon sputtering, which is not possible for Hg. In this work, we compare Hg measured in a reducing H 2 atmosphere 10 to measurements taken in a U...

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“…We split the surface excess entropy into three parts describing surface layering, capillary waves, and a surface double layer [2]. As expected the contribution from surface layering into ∆S is negative [1], whilst that contribution from capillary waves is positive. It was suggested [2] that the electric field in the double layer would contribute to the surface excess entropy with a positive sign if the layer thickness varies with T but the surface charge density does not.…”

Section: Introductionmentioning

confidence: 79%

Anomalous temperature dependence of the surface tension and capillary waves at a liquid-gallium surface

Kolevzon¹

1999

J. Phys.: Condens. Matter

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The temperature dependence of the surface tension γ(T ) at liquid gallium is studied theoretically and experimentally using light scattering from capillary waves. The theoretical model based on the Gibbs thermodynamics relates ∂γ/∂T to the surface excess entropy density −∆S. Although capillary waves contribute to the surface entropy with a positive sign, the effect of dipole layer on ∆S is negative. Experimental data collected at a free Ga surface in the temperature range from 30 • C to 160 • C show that ∂γ/∂T changes sign near 100 • C.

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Temperature-dependent behaviour of capillary waves at Hg - vapour and Hg - HgO interfaces

Cited by 7 publications

References 17 publications

Viscoelastic Behavior of 1-Dodecanol Monolayers Undergoing a Liquid−Solid Phase Transition. A Surface Quasielastic Light Scattering Study

Viscoelastic Behavior of 1-Dodecanol Monolayers Undergoing a Liquid−Solid Phase Transition. A Surface Quasielastic Light Scattering Study

X-ray reflectivity study of temperature-dependent surface layering in liquid Hg

Anomalous temperature dependence of the surface tension and capillary waves at a liquid-gallium surface

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