FTIR spectroscopic studies of layer systems transferred onto germanium supports

Vollhardt, D.; Wittig, M.; Maulhardt, Hans; Kunath, D.

doi:10.1007/bf01451521

Cited by 6 publications

(4 citation statements)

References 11 publications

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“…The value of K b for a long chain alkylamine is about 5 × 10 −4 ; therefore, in the neutral solution, the majority of the alkylamine molecules exist as RNH 3 + . It was reported that ODA monolayers transferred at pH = 7.5 contain mainly alkylammonium ion . In the present study (pH = 6.0), the amine groups of ODA LB films should be almost protonated, and this prediction was also demonstrated by the infrared spectrum of ODA LB films (see Supporting Information).…”

Section: Resultssupporting

confidence: 75%

“…It was reported that ODA monolayers transferred at pH ) 7.5 contain mainly alkylammonium ion. 31 In the present study (pH ) 6.0), the amine groups of ODA LB films should be almost protonated, and this prediction was also demonstrated by the infrared spectrum of ODA LB films (see Supporting Information). The strong bands at 1660 and 1560 cm -1 correspond to the antisymmetric and symmetric stretching modes of the NH 3 + , respectively.…”

supporting

confidence: 67%

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Nucleation and Growth of Glycine Crystals with Controllable Sizes and Polymorphs on Langmuir–Blodgett Films

Lü

Guang-hong

Zhai

et al. 2007

Crystal Growth & Design

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Control of crystal polymorph and size is very important in many application fields. Herein we demonstrate that Langmuir–Blodgett (LB) films of stearic acid (SA) and octadecylamine (ODA) can serve as templates and generate different polymorphs of glycine crystals. In the neutral aqueous solutions, γ-glycine crystallizes on LB films of ODA while the polymorphic outcome becomes the α-form on LB films of SA. These observed results could be explained by the electrostatic interactions and geometric lattice matching at the LB film/crystal interfaces, respectively. By keeping the appropriate supersaturation, we have successfully controlled the number of crystals grown on LB films; for example, in some certain cases, only one piece of crystal was grown on LB films in solution. Therefore, large crystals of centimeter size could be prepared. These experimental results suggest a new approach to produce an organic crystal with bulk scale.

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Section: Resultssupporting

confidence: 75%

supporting

confidence: 67%

Nucleation and Growth of Glycine Crystals with Controllable Sizes and Polymorphs on Langmuir–Blodgett Films

Lü

Guang-hong

Zhai

et al. 2007

Crystal Growth & Design

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“…In all spectra, it is not reasonable to compare intensities between samples because the exact molar concentrations and film thickness were impossible to correct for. Primary amines have been well characterized in the literature; − however, characterization is discussed here for the purpose of comparing to the quantum dot samples.…”

Section: Resultsmentioning

confidence: 99%

Characterization of Primary Amine Capped CdSe, ZnSe, and ZnS Quantum Dots by FT-IR: Determination of Surface Bonding Interaction and Identification of Selective Desorption

et al. 2011

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Surface ligands of semiconductor quantum dots (QDs) critically influence their properties and functionalities. It is of strong interest to understand the structural characteristics of surface ligands and how they interact with the QDs. Three quantum dot (QD) systems (CdSe, ZnSe, and ZnS) with primary aliphatic amine capping ligands were characterized primarily by FT-IR spectroscopy as well as NMR, UV-vis, and fluorescence spectroscopy, and by transmission electron microscopy (TEM). Representative primary amines ranging from 8 to 16 carbons were examined in the vapor phase, KBr pellet, and neat and were compared to the QD samples. The strongest hydrogen-bonding effects of the adsorbed ligands were observed in CdSe QDs with the weakest observed in ZnS QDs. There was an observed splitting of the N-H scissoring mode from 1610 cm(-1) in the neat sample to 1544 and 1635 cm(-1) when bound to CdSe QDs, which had the largest splitting of this type. The splitting is attributed to amine ligands bound to either Cd or Se surface sites, respectively. The effect of exposure of the QDs dispersed in nonpolar medium to methanol as a crashing agent was also examined. In the CdSe system, the Cd-bound scissoring mode disappeared, possibly due to methanol replacing surface cadmium sites. The opposite was observed for ZnSe QDs, in which the Se-bound scissoring mode disappeared. It was concluded that surface coverage and ligand bonding partners could be characterized by FT-IR and that selective removal of surface ligands could be achieved through introduction of competitive binding interactions at the surface.

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“…The tendency of the layer systems to change their ultrastructure forming crystals and the less favourable transfer properties in comparison with quartz prove that the interaction between germanium atoms of the support surface and polar groups of the monolayer is weak. This result is stabilized by FTIR-spectroscopic measurements using the ATR-technique because such interactions could not be proved by this method [14]. According to other papers [15,16] a water film is adsorbed on the quartz surface which cannot be displaced by fatty acids.…”

Section: Discussionmentioning

confidence: 92%

Evidence of lateral surface structure changes in transferred multilayer systems by electron microscopy

Vollhardt¹,

Richter‐Mendau²,

Wittig³

1984

Colloid & Polymer Sci

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Abstract:The substance-specific stability properties of transferred multilayer systems on germanium and quartz supports have been examined in the electron microscope. Typical micrographs with magnifications between 8 000 x and 40 000 x show that the surface structure of cadmium octadecanoate and octadecylammonium phosphate layer systems is dependent on the investigated parameters: type of substance, material of support, number of layers. Lateral structure rearrangement processes have been observed in the octadecanoate systems forming crystallites on both support materials and alllayer numbers. Similar irreversible transformations did not occur in transferred octadecylamine layer systems. The influence of the support material on the surface structure is interpreted as interaction differences between the support and the polar group of the first layer.

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FTIR spectroscopic studies of layer systems transferred onto germanium supports

Cited by 6 publications

References 11 publications

Nucleation and Growth of Glycine Crystals with Controllable Sizes and Polymorphs on Langmuir–Blodgett Films

Nucleation and Growth of Glycine Crystals with Controllable Sizes and Polymorphs on Langmuir–Blodgett Films

Characterization of Primary Amine Capped CdSe, ZnSe, and ZnS Quantum Dots by FT-IR: Determination of Surface Bonding Interaction and Identification of Selective Desorption

Evidence of lateral surface structure changes in transferred multilayer systems by electron microscopy

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