Anke Krüger

Surface functionalisation of detonation diamond suitable for biological applications

Detonation diamond is a promising material for biological applications due to its biocompatibility and fluorescence from lattice defects. Here we report on the organic functionalisation method for small detonation diamond agglomerates. After surface homogenisation by reduction and grafting of a silane linker, amino acids have been coupled to the diamond surface and the formation of a small peptide has been achieved. These novel functionalised diamond materials are potentially useful for the synthesis of surface-bound peptides and for the attachment of biologically active building blocks, which could be used in drug delivery and fluorescence marker applications.

Fluorescence emission in fluid solution and supersonic jet of symmetrical bisbenzenes incorporating a three membered flexible chain

Abstract Intramolecular excimer formation in symmetrical bichromophore compounds consisting of two benzene, anisole, and 2,6-dimethylbenzene groups connected by a highly flexible O-CH2-O chain has been evidenced from steady state and time resolved fluorescence studies. The thermodynamic and kinetic parameters have been determined in methanol and for one of them in methylcyclohexane as a function of temperature. While the activation energy for the conformational change required for excimer formation is similar for both solvents, the preexponential factors deduced from Arrhenius plots appear to be larger in methanol than in methylcyclohexane. The parallel investigation of fluorescence excitation and dispersed emission spectra of bis-p-methoxy-phenoxymethane in supersonic expansion has shown that two conformers coexist in the jet and that the intrinsic barrier for excimer formation in the isolated molecule is larger than 2.3 kcal mol−1.

Diamond films: Initial CVD growth stage using nanodiamonds as nucleation centers

Scanning electron microscopy is used to study features of a mechanism operating in the initial growth stages during the CVD of diamond films on nucleation centers representing predeposited nanodiamonds obtained by method of detonation synthesis.

Growth of Diamond Films on Crystalline Silicon by Hot-Filament Chemical Vapor Deposition

The effect of hot-filament chemical vapor deposition conditions on the phase composition of diamond films grown on a silicon substrate was studied. The growth conditions providing the highest content of diamond phase at a growth rate of about 1 µm/h were ascertained.

Carbon nanotubes as elements to focus electron beams by Fresnel diffraction

Fresnel diffraction of electrons at curved edges can be used to focus electrons onto a spot when the concave side of the edge is transparent. It is shown that short multi-wall carbon nanotubes with diameters of the inner hollow core of a few nanometers act as electron focusers when they are aligned parallel to the beam in an electron microscope. The electron beam is focused onto the projected center of the tube, where an amplification of the electron intensity by several times can be attained.