Single molecule diffusion at step edges

Schob, Arne; Cichos, Frank

doi:10.1016/j.cplett.2009.11.028

Cited by 4 publications

(6 citation statements)

References 27 publications

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“…Figure (a,b) shows the obtained broad distributions of diffusion coefficients D traj calculated via mean square displacements along identified trajectories. , While Figure (a) collects all trajectories, Figure (b) puts the emphasis on mobility by selecting those trajectories, which exceed a lateral area of 1.3 μm 2 . The broad distributions of D traj seen in Figure (a and b) point to heterogeneous tracer diffusion, in agreement with recent reports. ,, The qualitative overall feature is that diffusion becomes slower with decreasing h .…”

Section: Results and Discussionsupporting

confidence: 91%

“…Previous work on tracer diffusion in ultrathin TEHOS films on silica substrates with 100 nm oxide revealed a considerable slowdown in comparison to bulk measurements by more than one order in magnitude. ,, Further information on the diffusion in dependence on the distance to the solid–liquid interface could be obtained from a long-time study on thinning TEHOS films on silicon with 100 nm thermal oxide. , Here we report an extension of this study, especially by FCS experiments on 100 Å thick films, and a discussion in parallel to the results from the ellipsometry study, thus amending the previously published interpretations.…”

Section: Results and Discussionsupporting

confidence: 53%

“…The question, whether the observed liquid layering has an influence on the molecular dynamics of the liquid, motivated optically detected single molecule tracer experiments in confined liquids. Thereby, a slowdown of the tracer diffusion in wetting precursor layers of liquid droplets, in ultrathin liquid films and in a liquid film at a step edge on mica, was observed. − Furthermore, single molecule tracking (SMT) experiments revealed a broad distribution of diffusion coefficients, − which indicates heterogeneous diffusion. The observation of heterogeneous diffusion was attributed to liquid layering. ,, However, it has to be mentioned, that direct evidence of layering was obtained from investigation (by X-ray and ellipsometry) only for films on silicon substrates with a thin (native) oxide layer.…”

Section: Introductionmentioning

confidence: 99%

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Influence of van der Waals Interactions on Morphology and Dynamics in Ultrathin Liquid Films at Silicon Oxide Interfaces

2013

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Single molecule tracer diffusion studies of evaporating (thinning) ultrathin tetrakis-2-ethylhexoxysilane (TEHOS) films on silicon with 100 nm thermal oxide reveal a considerable slowdown of the molecular mobility within less than 4 nm above the substrate (corresponding to a few molecular TEHOS layers). This is related to restricted mobility and structure formation of the liquid in this region, in agreement with information obtained from a long-time ellipsometric study of thinning TEHOS films on silicon substrates with 100 nm thermal or 2 nm native oxide. Both show evidence for the formation of up to four layers. Additionally, on thermal oxide, a lateral flow of the liquid is observed, while the film on the native oxide forms an almost flat surface and shows negligible flow. Thus, on the 2 nm native oxide the liquid mobility is even more restricted in close vicinity to the substrate as compared to the 100 nm thermal oxide. In addition, we found a significantly smaller initial film thickness in case of the native oxide under similar dipcoating conditions. We ascribe these differences to van der Waals interactions with the underlying silicon in case of the native oxide, whereas the thermal oxide suffices to shield those interactions.

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Section: Results and Discussionsupporting

confidence: 91%

Section: Results and Discussionsupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

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Influence of van der Waals Interactions on Morphology and Dynamics in Ultrathin Liquid Films at Silicon Oxide Interfaces

2013

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“…Single-molecule FCS was used to map the vortexlike hydrodynamic flow at a T-shaped junction of microchannels [127], and to acquire direct kinetics measurements in a rapid continuous flow mixer using zero-mode waveguides [128]. A modified surface forces apparatus for single-molecule tracking and a number of data analysis methods were introduced for mapping flow profiles in shear flows of ultrathin liquid films [129][130][131].…”

Section: Other Applicationsmentioning

confidence: 99%

Recent advances in single‐molecule detection on micro‐ and nano‐fluidic devices

Liu¹,

Qu²,

Luo³

et al. 2011

Electrophoresis

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Single-molecule detection (SMD) allows static and dynamic heterogeneities from seemingly equal molecules to be revealed in the studies of molecular structures and intra- and inter-molecular interactions. Micro- and nanometer-sized structures, including channels, chambers, droplets, etc., in microfluidic and nanofluidic devices allow diffusion-controlled reactions to be accelerated and provide high signal-to-noise ratio for optical signals. These two active research frontiers have been combined to provide unprecedented capabilities for chemical and biological studies. This review summarizes the advances of SMD performed on microfluidic and nanofluidic devices published in the past five years. The latest developments on optical SMD methods, microfluidic SMD platforms, and on-chip SMD applications are discussed herein and future development directions are also envisioned.

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“…The spontaneous (thermal) or field-driven motions of the individual molecules are then followed by wide-field fluorescence video microscopy or by beam scanning confocal methods. − Figure a provides representative examples of the videos obtained. The molecular motions observed are tracked using computer software designed to locate the molecules in each frame and link them into trajectories (see Figure b). , Such methods have recently been used to study 2D and 3D diffusion in films, − on surfaces, − in polymers, − and in gels and to observe and quantify surface adsorption and confinement effects . In the case of 1D nanostructured materials, the focus of this Perspective, such methods allow for visualization of the incorporated nanostructures and their ability to confine and guide probe molecule motions. , Quantitative data on the local orientation and organization of 1D nanostructures are also obtained, as are clues on the origins and impacts of materials disorder .…”

mentioning

confidence: 99%

Following Single Molecules to a Better Understanding of Self-Assembled One-Dimensional Nanostructures

Higgins

Tran-Ba

Ito

2013

J. Phys. Chem. Lett.

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Single-molecule tracking (SMT) methods are now being employed to probe the morphologies and mass-transport characteristics of self-assembled one-dimensional (1D) nanostructures. Such nanostructures are found in surfactant-templated mesoporous metal oxides, phaseseparated block copolymers, and lyotropic liquid-crystal mesophases. This Perspective begins with a review of investigations in which SMT methods have been employed for in situ visualization of 1D nanostructures and their ability to guide and support 1D diffusion of fluorescent probe molecules. New orthogonal regression methods for the quantitative characterization of 1D nanostructure alignment and order are subsequently discussed. Recent investigations in which the confined orientational motions of single molecules are probed by single-molecule emission polarization measurements are highlighted. These data are used to access high-precision estimates of the effective lateral nanostructure dimensions. The results reveal the important role played by nanoconfined solvents and soft material nanostructures in restricting probe molecule motions. M aterials incorporating ordered, oriented 1D nanostructures have myriad potential applications as membranes and monoliths for use in chemical sensing, catalysis, separations, batteries, and fuel cells. 1,2 Interest in these materials arises in part because both nanostructure size and local chemical composition can be controlled to achieve chemical selectivity. For the purposes of this Perspective, relevant materials include both organic and inorganic assemblies such as lyotropic liquid-crystal mesophases, 3,4 surfactant-templated mesoporous metal oxides, 1,5−14 and phase-separated block copolymers. 2,15,16 Before any of these can be employed in commercial devices, much remains to be learned about the local alignment, organization, continuity, and accessible internal dimensions of their 1D nanostructures. This Perspective highlights recent investigations of these attributes by in situ single-molecule tracking (SMT) methods.One-dimensional nanostructures are commonly investigated by small-angle X-ray and neutron scattering (SAXS and SANS), scanning and transmission electron microscopy (SEM and TEM), and atomic force microscopy (AFM). 1,2,17−20 SAXS and SANS have provided valuable data on the materials' periodicity and, hence, nanostructure size and organization. In porous materials, pore size and surface area are frequently determined by gas adsorption measurements. 21 Scattering anisotropy data have revealed the 1D nature of many such materials and have yielded quantitative measurements of average nanostructure order. 12 SEM, TEM, and AFM afford a microscopic view of these same characteristics. Unfortunately, such methods provide little or no direct information on the partitioning and mass-transport characteristics of greatest relevance to many of their applications.The dynamics and directionality of molecular mass transport within 1D nanostructures have previously been investigated by nuclear magnetic resonance (NMR) sp...

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Single molecule diffusion at step edges

Cited by 4 publications

References 27 publications

Influence of van der Waals Interactions on Morphology and Dynamics in Ultrathin Liquid Films at Silicon Oxide Interfaces

Influence of van der Waals Interactions on Morphology and Dynamics in Ultrathin Liquid Films at Silicon Oxide Interfaces

Recent advances in single‐molecule detection on micro‐ and nano‐fluidic devices

Following Single Molecules to a Better Understanding of Self-Assembled One-Dimensional Nanostructures

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