Optical Microscopy in the Nano-World

Scanning near-field optical microscopy (SNOM) is an optical microscopy whose resolution is not bound to the diffraction limit. It provides chemical information based upon spectral, polarization and/or fluorescence contrast images. Details as small as 20 nm can be recognized. Photophysical and photochemical effects can be studied with SNOM on a similar scale. This article reviews a good deal of the experimental and theoretical work on SNOM in Switzerland

Optical microscopy in the nano-world

Scanning near-field optical microscopy (SNOM) is an optical microscopy whose resolution is not bound to the diffraction limit. It provides chemical information based upon spectral, polarization and/or fluorescence contrast images. Details as small as 20 nm can be recognized. Photophysical and photochemical effects can be studied with SNOM on a similar scale. This article reviews a good deal of the experimental and theoretical work on SNOM in Switzerland

NMR SHIFT MEASUREMENTS OF Mn DOPED SnTe COMPOUNDS

Nous avons étudié par résonance magnétique nucléaire (RMN) le système (SnTe)100-xMnx. Le déplacement de Knight des noyaux de 119Sn et 125Te pour SnTe non-dopé est indépendant de la température entre 4,2 et 300 K. La variation du déplacement de Knight K(Sn) en fonction de la concentration de Mn, à température ambiante, nous a permis de tirer une valeur de l'intégrale d'échange entre les moments localisés et les porteurs de charge ; J = (0,22 ± 0,05) eV.We have studied by nuclear magnetic resonance (NMR) the system (SnTe)100-x Mnx. The knight shift of 119Sn and 125Te nuclei for undoped SnTe is temperature independent between 4.2 and 300 K. The variation of the Knight shift K(Sn) as a function of Mn concentration, at room temperature, has allowed us to obtain a value of the exchange integral between localized moments and charge carriers ; J = (0.22 ± 0.05) eV

Influence of surface and protein modification on immunoglobulin G adsorption observed by scanning force microscopy.

Scanning force microscopy has been used successfully to produce images of individual protein molecules. However, one of the problems with this approach has been the high mobility of the proteins caused by the interaction between the sample and the scanning tip. To stabilize the proteins we have modified the adsorption properties of immunoglobulin G on graphite and mica surfaces. We have used two approaches: first, we applied glow discharge treatment to the surface to increase the hydrophilicity, favoring adhesion of hydrophilic protein molecules; second, we used the arginine modifying reagent phenylglyoxal to increase the protein hydrophobicity and thus enhance its adherence to hydrophobic surfaces. We used scanning force microscopy to show that the glow discharge treatment favors a more homogeneous distribution and stronger adherence of the protein molecules to the graphite surface. Chemical modification of the immunoglobulin caused increased aggregation of the proteins on the surface but did not improve the adherence to graphite. On mica, clusters of modified immunoglobulins were also observed and their adsorption was reduced. These results underline the importance of the surface hydrophobicity and charge in controlling the distribution of proteins on the surface

Influence of surface treatments on the physical and biological properties of titanium

The physical and biological properties of titanium modified by different surface treatment processes were compared. The influence of the treatments on the chemical composition, wettability and roughness of the titanium surfaces were analyzed. As an index of biological activity, fibronectin adsorption to each type of surface and promotion of bacterial adhesion were studied. The different surface treatments had no effect on the chemical composition of the titanium oxide, the adsorption of fibronectin, and the promotion of S. aureus adhesion. The main physical difference between the surface treatments was the roughness generated by the acid attack which favors bone ingrowth.Link_to_subscribed_fulltex