Monolayer Structure (monolayer + structure)

Distribution by Scientific Domains

Selected Abstracts

Transmission Fluctuation Spectrometry in Concentrated Suspensions.

Part Three: Measurements
Abstract The theory of transmission fluctuation spectrometry (TFS) was developed for particle size analysis in flowing particle suspensions, whereby the statistical transmission fluctuations are used to extract the particle size distribution (PSD) and particle concentration. In the previous parts of this publication high concentration effects on TFS were investigated theoretically and by simulation. This work presents a study on TFS measurements in concentrated suspensions. By introducing an empirical correction to include the high concentration effects from both the monolayer structure and particle overlapping in the inversion algorithm, it is possible to obtain the particle size distribution and particle concentration over broad ranges of particle sizes and concentrations. [source]

Poly[triaqua(,4 -4-carboxybenzenesulfonato-,4O:O,:O,,:O,,,)(4-carboxybenzenesulfonato-,O)strontium(II)]

G. Prochniak
This study presents the coordination modes and two-dimensional network of a novel strontium(II) coordination polymer, [Sr(C7H5O5S)2(H2O)3]n. The eight-coordinate Sr2+ ion is in a distorted bis-disphenoidal coordination environment, surrounded by four sulfonate and one carboxyl O atom from five benzenesulfonate ligands, two of which are symmetry unique, and by three O atoms from three independent aqua ligands. The compound exhibits a monolayer structure with coordination bonds within and hydrogen bonds between the layers. The ,4 acid ligand bridges the metal ions in two dimensions to form a thick undulating monolayer with a hydrophobic interior and hydrophilic surfaces. A second independent monoanion is arranged outward from both sides of the monolayer and serves to link adjacent monolayers via carboxyl,water and water,carboxyl hydrogen bonds. [source]

Structural Evolution of Self-Assembled Alkanephosphate Monolayers on TiO2,

CHEMPHYSCHEM, Issue 14 2008
Hong-Bo Liu
Conformation and orientation: The formation of self-assembled monolayers (SAM) of hexadecyl phosphate on macroscopically flat TiO2 surfaces is studied by using IR spectroscopy (see picture). The evolution of a well-organized monolayer structure can be readily monitored from the conformational and orientational ordering of the alkyl chains. [source]

Thickness-Dependent Structural Evolutions and Growth Models in Relation to Carrier Transport Properties in Polycrystalline Pentacene Thin Films,

H.-L. Cheng
Abstract Thickness-dependent crystal structure, surface morphology, surface energy, and molecular structure and microstructure of a series of polycrystalline pentacene films with different film thickness ranging from several monolayers to the several hundred nanometers have been investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), contact angle meter, and Raman spectroscopy. XRD studies indicate that thin film polymorphs transformation behaviours are from the orthorhombic phase to the thin-film phase and then to the triclinic bulk phase as measured by the increased tilt angle (,tilt) of the pentacene molecule from the c- axis toward the a- axis. We propose a growth model that rationalizes the ,tilt increased along with increasing film thickness in terms of grain size and surface energy varying with film growth using AFM combined with contact angle measurements. The vibrational characterizations of pentacene molecules in different thickness films were investigated by Raman spectroscopy compared to density functional theory calculations of an isolated molecule. In combination with XRD and AFM the method enables us to distinguish the molecular microstructures in different thin film polymorphs. We proposed a methodology to probe the microscopic parameters determining the carrier transport properties based on Davydov splitting and the characteristics of aromatic C,C stretching modes in Raman spectra. When compared to the triclinic bulk phase at a high thickness, we suggest that the first few monolayer structures located at the dielectric surface could have inferior carrier transport properties due to weak intermolecular interactions, large molecular relaxation energy, and more grain boundaries. [source]