Das Verhalten von Oberfläche zu Oberflächendruck von Fettsäure-Einzelschicten auf Mehrfachkomponenten-Substraten

Ohne Zusammenfassung     

Adsorption of 1,3‐Benzenedithiol and 1,3‐Benzenedimethanethiol on Gold Surfaces

The adsorption characteristics of 1,3‐benzenedithiol (1,3‐BDT) and 1,3‐benzenedimethanethiol (1,3‐BDMT) on Au surfaces are investigated by means of surface‐enhanced Raman scattering, UV/Vis absorption spectroscopy, and cyclic voltammetry (CV). 1,3‐BDMT is found to adsorb via two S–Au linkages at concentrations below monolayer coverage, but to have an upright geometry as the concentration increases on Au nanoparticles. On the other hand, 1,3‐BDT is found to adsorb by forming two S–Au linkages, regardless of concentration, based on the disappearance of the ν(SH)_free stretching band. Because of the absence of the methylene unit, 1,3‐BDT appeares not to self‐assemble efficiently on Au surfaces. The UV/Vis absorption spectroscopy and CV techniques are also applied to check the formation of self‐assembled monolayers of 1,3‐BDT and 1,3‐BDMT on Au. Density functional theory calculations based on a simple adsorption model using an Au₈ cluster are performed to better understand the nature of the adsorption characteristics of 1,3‐BDT and 1,3‐BDMT on Au surfaces.     

Paramagnetic gold nanostructures for dual modal bioimaging and phototherapy of cancer cells

Paramagnetic gold nanostructures were synthesized by combining the paramagnetism of gadolinium with the plasmonic properties of gold nanoparticles and used for dual modal (MRI and optical) imaging and phototherapy of breast cancer cells.     

Electronic structure and magnetism in transition metals doped 8-hydroxy-quinoline aluminum

We report the room-temperature ferromagnetism in transition metals (Co, Ni)-doped 8-hydroxy-quinoline aluminum (Alq3) by thermal coevaporation of high purity metal and Alq3 powders. For 5% Co-doped Alq3, a maximum magnetization of approximately 0.33 microB/Co at 10 K was obtained and ferromagnetic behavior was observed up to 300 K. The Co atoms interact chemically with O atoms and provide electrons to Alq3, forming new states acting as electron trap sites. From this, it is suggested that ferromagnetism may be associated with the strong chemical interaction of Co atoms and Alq3 molecules.     

Two-photon fluorescent turn-on probe for lipid rafts in live cell and tissue

We report a new two-photon fluorescence turn-on probe 6-[(E)-3-oxo-1-dodecenyl]-2-[N-methyl-N-(carboxymethyl)amino]naphthalene (CL2) that is designed specifically for visualizing lipid rafts in living cells and tissues. This probe emits much brighter two-photon excited fluorescence in lipid rafts than in non-raft domains and allows direct visualization of the lipid rafts in the live cells and pyramidal neuron layer of the CA1 region at a depth of 100-250 mum in live tissues using two-photon microscopy.     

Connection between the 2-body energy of the Kaxiras-Pandey and the Biswas-Hamann potentials

Relationship among interatomic potential functions can be useful in shedding insight on the extent of similarity, and in obtaining a potential function from parameters of another potential function. The 2-body portion of the Biswas-Hamann (BH) and the Kaxiras-Pandey (KP) potential functions are related by equating both functions, as well as their corresponding derivatives up to the third order at the equilibrium bond length. Validity of the parametric relationship is verified by plotting the loose form of the 2-body BH potential in terms of KP parameters and comparing it with the KP potential function. The parametric relationships developed herein are then compared with those that concern other potential functions, with particular emphasis on the scaling factors.     

Laser-effected darkening in TPEs with TiO2 additives

Investigations were carried out for laser-effected darkening and damage-free laser marking on thermoplastic elastomers (TPEs). Titanium dioxide (TiO₂) was studied as the laser-sensitive additive to the TPEs for its role in enhancing laser marking contrast and its effect on the TPE properties. Laser beam characteristics, processing variables and percentage loading of TiO₂ in the TPEs were found to have significant effect on the marking contrast. Surface damage-free and high contrast marking have been achieved with short pulse UV lasers. The laser-effected darkening was found to penetrate into the material in the order of a few tens of microns. XPS analysis was carried out to understand the laser-effected darkening mechanism. Potential applications of the technique are highlighted.     

Molecular Recognition in Self‐Assembled Integrated Circuits: Getting Smaller while under Control

Available in small print : Block copolymer lithography has great potential for reducing the size and fabrication time of integrated circuits. Hydrogen‐bonding‐mediated molecular recognition in self‐assembly processes can be used to produce highly ordered square arrays of block copolymers on the surface of a silicon substrate (see picture).

     

Self-assembled monolayers on Pt(111): molecular packing structure and strain effects observed by scanning tunneling microscopy

Self-assembled monolayers (SAMs) of octanethiol and benzeneethanethiol were deposited on clean Pt(111) surfaces in ultrahigh vacuum (UHV). Highly resolved images of these SAMs produced by an in situ scanning tunneling microscope (STM) showed that both systems organize into a super-structure mosaic of domains of locally ordered, closely packed molecules. Analysis of the STM images indicated a (square root 3 x square root 3)R30 degrees unit cell for the octanethiol SAMs and a 4(square root 3 x square root 3)R30 degrees periodicity based on 2 x 2 basic molecular packing for the benzeneethanethiol SAMs under the coverage conditions investigated. SAMs on Pt(111) exhibited differences in molecular packing and a lower density of disordered regions than SAMs on Au(111). Electron transport measurements were performed using scanning tunneling spectroscopy. Benzeneethanethiol/Pt(111) junctions exhibited a higher conductance than octanethiol/Pt(111) junctions.