Anchoring Phase of Liquid Crystal Mixtures Studied by Scanning Tunneling Microscopy

Iwakabe, Yasushi; Kondo, K.; Oh-hara, Syuichi; Mukoh, Akio; Hara, Masahiko; Sasabe, Hiroyuki

doi:10.1021/la00021a050

Cited by 18 publications

(3 citation statements)

References 4 publications

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“…In this study, we did not utilize STM , but AFM for the observation of domains. This is because AFM seems to be more suitable for the topological characterization of nonconductive films, especially for the discrimination of the alkyl chain length (the height of SAM domains).…”

Section: Introductionmentioning

confidence: 99%

Surface Phase Behavior of n-Alkanethiol Self-Assembled Monolayers Adsorbed on Au(111): An Atomic Force Microscope Study

et al. 1997

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n-Alkanethiol (C n H2n+1SH) self-assembled monolayers (SAMs) adsorbed on Au(111) were studied with an atomic force microscope (AFM) to confirm the influence of the lateral interaction between adsorbed thiols on the film morphology. Two experiments were performed: firstly, a study of the domain formation at the initial stage of SAM growth (single component) and, secondly, investigations of the coadsorption phenomenon in mixed SAMs composed of two alkanethiols having different chain lengths. For the kinetics study, Au(111) was immersed into the 10-2 mM ethanol solutions with the single component alkanethiol (C4H9SH, C12H25SH, or C18H37SH), for varying times (1 s to 10 min). In all cases, the film coverage increased as the immersion time became longer, and finally the surface was totally covered with thiols after an immersion time of 3 min or more. Clear island formations were observed in the partially covered C12H25SH and C18H37SH SAMs, while C4H9SH formed meshlike domains. The mixed SAMs were prepared by immersing Au(111) into 1 mM ethanol solutions with mixed alkanethiols (C4H9SH/C18H37SH) of various compositions, R soln = [C4H9SH]/[C18H37SH] = 1/1 to 100/1, for a time of 1 h. Clear phase separation was observed at R soln = 20/1 and 40/1. Above or below these compositions, the film surface appeared very flat, covered with a nearly single component, C4H9SH or C18H37SH, respectively. This is the first systematic study of the surface phase behavior of alkanethiol SAMs by AFM imaging. It reveals more direct information about the film morphology than previous studies with conventional surface analytical techniques such as X-ray photoelectron spectroscopy, ellipsometry, contact angles, etc.

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Section: Introductionmentioning

confidence: 99%

Surface Phase Behavior of n-Alkanethiol Self-Assembled Monolayers Adsorbed on Au(111): An Atomic Force Microscope Study

et al. 1997

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“…Thus, STM imaging can provide an approach for obtaining a detailed characterization of the LC/solid interface. In such adsorbed monolayers, it is widely accepted that, in general, the aromatic moieties image brighter (that is, exhibit more efficient tunneling) by STM than the aliphatic regions. , However, examples of nonaromatic moieties imaging brightly are known, and a general theory of STM imaging of organic molecules is still lacking.…”

Section: Introductionmentioning

confidence: 99%

Scanning Tunneling Microscopy Images of a Novel Dimeric Liquid Crystal on Graphite

et al. 1996

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Scanning tunneling microscopy (STM) images of a side-by-side dimeric liquid crystal adsorbed on graphite suggest an unusual structure for the monolayer. Instead of the contact with the graphite being maximized, two of the alkyl tails appear to be nearly normal to the surface. Calculations suggest that this may be due to the substitution of one of the aromatic rings in the core, which causes an alkoxy tail to prefer an orientation perpendicular to the aromatic core rather than the usual coplanar orientation. STM images taken at various bias voltages correlate strongly to the aromatic "cores" of the molecules, but do not appear to correlate to the highest occupied moleculear orbital or lowest unoccupied molecular orbital.

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“…A possible effect of the reduction in miscibility is the formation of domains of pure C 12 TAB liquid crystal and of pure C 18 TAB mesophase intercalated between each other, as detected in other systems [53]. It must be pointed out that the coating of the support was formed by a superposition of several bilayers.…”

Section: Interaction Parameter Surfactant-surfactantmentioning

confidence: 86%

Miscibility of anhydrous cationic surfactant mixtures

Bardavid

Schulz

Arancibia

2010

Journal of Molecular Liquids

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Anchoring Phase of Liquid Crystal Mixtures Studied by Scanning Tunneling Microscopy

Cited by 18 publications

References 4 publications

Surface Phase Behavior of n-Alkanethiol Self-Assembled Monolayers Adsorbed on Au(111): An Atomic Force Microscope Study

Surface Phase Behavior of n-Alkanethiol Self-Assembled Monolayers Adsorbed on Au(111): An Atomic Force Microscope Study

Scanning Tunneling Microscopy Images of a Novel Dimeric Liquid Crystal on Graphite

Miscibility of anhydrous cationic surfactant mixtures

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