The Effect of Surface Ions on Water Adsorption to Mica

Te, Balmer; Hk, Christenson; Spencer, Nicholas D.; Heuberger, Manfred

doi:10.1021/la702391m

Cited by 80 publications

(173 citation statements)

References 29 publications

(57 reference statements)

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“…Since both mica membranes have the same thickness, a symmetric arrangement is obtained. Permanently adsorbed water is found on the inner and outer mica surfaces as is expected from their hydrophilic character [15][16][17]. Even in a dry environment, an adsorbed water layer is present at the surface planes of potassium ions which we assume to be immobile in our study.…”

supporting

confidence: 54%

X-ray reflectivity reveals equilibrium density profile of molecular liquid under nanometre confinement

Perret¹,

Nygård²,

Satapathy³

et al. 2009

Europhys. Lett.

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-A silane (tetrakis(trimethylsiloxy)silane) has been confined within a space of a few molecular diameters (9Å) between two atomically flat opposing mica membranes. The liquid's electron density profile along the confinement direction has been determined by synchrotron X-ray reflectivity for film thicknesses of 8.58 and 11.22 nm. We find the liquid's molecules to be strongly layered at layer distances significantly larger than the effective molecular diameter. The considerable free volume enables the confined liquid to retain its liquid properties.A liquid which is confined within a slit or pore exhibits properties markedly different from the bulk liquid if it is confined within a space of only a few molecular diameters in size [1]. Such "extreme confinement" imposes a structural ordering to the liquid, which in turn will affect many of the liquid's properties. A considerable part of confined-fluids research has been concerned with measurements of the normal and lateral forces acting between two approaching surfaces in a liquid medium. Typically, oscillatory forces are observed having a periodicity of just below one molecular diameter and an exponential decay of comparable length scale [2][3][4][5]. Discrete steps in film thickness are observed, which are commonly interpreted as layering transitions through expulsions of single molecular layers. However, unambiguous electrondensity profiles providing proof of such liquid layering have not yet been experimentally determined. More recently, synchrotron X-ray diffraction from various single solid-liquid interfaces and free surfaces revealed structural ordering [6][7][8][9][10][11]. A recent structural investigation of liquid within a nanometre-sized gap reported thickness quantization between silicon surfaces at externally forced surface separations [12].(a) E-mail: friso.vanderveen@psi.ch Using X-ray reflectivity (XRR) [13] as a function of perpendicular momentum transfer q ⊥ we have determined the electron density profile along the confinement direction of the spherical, non-polar liquid tetrakis(trimethylsiloxy)silane (TTMSS) having a molecular diameter of 9.0Å [8]. The liquid was confined between flat surfaces and the gap width between the surfaces was allowed to equilibrate in the absence of external forces. The confining walls were formed by a pair of (001)-oriented single-crystal surfaces of muscovite mica. The confinement configuration can be regarded as a free-standing single crystal which is interrupted by an ultrathin film of fluid. The advantage of using a crystal lies in its known structure and in its smooth surface provided it is free of atomic steps. The latter is a prerequisite for resolving distinct electron density peaks in the confined liquid. Figure 1 shows a schematic of the confinement geometry and the molecular structure of the mica crystal and TTMSS. Muscovite mica H 2 KAl 3 (SiO 4 ) 3 is a stack of aluminum silicate sheets separated by sheets of potassium ions. The muscovite (001) planes are easily cleaved due to the absence of cova...

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supporting

confidence: 54%

X-ray reflectivity reveals equilibrium density profile of molecular liquid under nanometre confinement

Perret¹,

Nygård²,

Satapathy³

et al. 2009

Europhys. Lett.

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“…The requirement of leaving a finite value of height for the films on the tip's and sample's surfaces might be due to a solidlike nature of the first water bilayers adsorbed on the surface of BaF2(111). 31 Nevertheless, it could also be affected by the presence of ions, 49 hydration shells and the possible dynamics of squeeze-out of the water film. At this point, we believe that careful control experiments should be performed to establish the origins of this effect.…”

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confidence: 99%

Subharmonic excitation in amplitude modulation atomic force microscopy in the presence of adsorbed water layers

Santos¹,

Barcons

Verdaguer

et al. 2011

Journal of Applied Physics

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Dielectrophoretic assembly and atomic force microscopy modification of reduced graphene oxide J. Appl. Phys. 110, 114515 (2011) Quasi in situ scanning force microscope with an automatic operated reaction chamber Rev. Sci. Instrum. 82, 113709 (2011) Mapping of conservative and dissipative interactions in bimodal atomic force microscopy using open-loop and phase-locked-loop control of the higher eigenmode Appl. Phys. Lett. 99, 074103 (2011) Wideband phase-locked loop circuit with real-time phase correction for frequency modulation atomic force microscopy Rev. Sci. Instrum. 82, 073707 (2011) Additional information on J. Appl. Phys. In ambient conditions, nanometric water layers form on hydrophilic surfaces covering them and significantly changing their properties and characteristics. Here we report the excitation of subharmonics in amplitude modulation atomic force microscopy induced by intermittent water contacts. Our simulations show that there are several regimes of operation depending on whether there is perturbation of water layers. Single period orbitals, where subharmonics are never induced, follow only when the tip is either in permanent contact with the water layers or in pure noncontact where the water layers are never perturbed. When the water layers are perturbed subharmonic excitation increases with decreasing oscillation amplitude. We derive an analytical expression which establishes whether water perturbations compromise harmonic motion and show that the predictions are in agreement with numerical simulations. Empirical validation of our interpretation is provided by the observation of a range of values for apparent height of water layers when subharmonic excitation is predicted.

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“…The hygroscopicity of mica is expected to play a role in the described processes. The hygroscopicity and Langmuir isotherm studies on mica are available in literature but only for room temperature where the sample and environment are at equilibrium (Balmer et al, 2008;Beaglehole et al, 1991;Hu et al, 1995). Such studies at supercooled surfaces are worth doing and could be a topic of future work.…”

Section: Introductionmentioning

confidence: 99%

Direct molecular-level characterization of different heterogeneous freezing modes on mica – Part 1

Abdelmonem

2017

Atmos. Chem. Phys.

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Abstract. The mechanisms behind heterogeneous ice nucleation are of fundamental importance to the prediction of the occurrence and properties of many cloud types, which influence climate and precipitation. Aerosol particles act as cloud condensation and freezing nuclei. The surface-water interaction of an ice nucleation particle plays a major, not well explored, role in its ice nucleation ability. This paper presents a real-time molecular-level comparison of different freezing modes on the surface of an atmospherically relevant mineral surface (mica) under varying supersaturation conditions using second-harmonic generation spectroscopy. Two sub-deposition nucleation modes were identified (one-and two-stage freezing). The nonlinear signal at the water-mica interface was found to drop following the formation of a thin film on the surface regardless of (1) the formed phase (liquid or ice) and (2) the freezing path (one or two step), indicating similar molecular structuring. The results also revealed a transient phase of ice at water-mica interfaces during freezing, which has a lifetime of around 1 min. Such information will have a significant impact on climate change, weather modification, and the tracing of water in hydrosphere studies.

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The Effect of Surface Ions on Water Adsorption to Mica

Cited by 80 publications

References 29 publications

X-ray reflectivity reveals equilibrium density profile of molecular liquid under nanometre confinement

X-ray reflectivity reveals equilibrium density profile of molecular liquid under nanometre confinement

Subharmonic excitation in amplitude modulation atomic force microscopy in the presence of adsorbed water layers

Direct molecular-level characterization of different heterogeneous freezing modes on mica – Part 1

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