Optical microscopy compared with electron

Optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) data obtained from the surface of metallographic section of initial alloy were compared with those from the surface subjected to hydrogen... 

Optical microscopy offers the possibility to visualize directly polymeric vesicles under physiological conditions. It is not necessary to dry or stain specimens instead, they can be kept in aqueous buffer. The major drawback of light microscopy compared to electron microscopy is the limited resolution, due to which it is mandatory to have polymersomes of large size giant vesicles with diameters above one micron are best suited for such studies. 

Unfortunately, the price that is paid for the convenience and capability of fluorescence microscopy is that of a relatively poor spatial resolution when compared with electron or X-ray microscopy. The size of the smallest details on a sample that can still be resolved is known as the resolution of the miaoscope. In optical microscopy, this fundamental limitation is roughly equal to half the wavelength of the used light, which typically corresponds to about 250 nm for blue-green excitation light (500 nm). In modem high-end research microscopes, this resolution limit is not due to technical or design issues, but solely determined by this apparently fundamental law of nature. 

An unusually extensive battery of experimental techniques was brought to bear on these comparisons of enantiomers with their racemic mixtures and of diastereomers with each other. A very sensitive Langmuir trough was constructed for the project, with temperature control from 15 to 40°C. In addition to the familiar force/area isotherms, which were used to compare all systems, measurements of surface potentials, surface shear viscosities, and dynamic suface tensions (for hysteresis only) were made on several systems with specially designed apparatus. Several microscopic techniques, epi-fluorescence optical microscopy, scanning tunneling microscopy, and electron microscopy, were applied to films of stearoylserine methyl ester, the most extensively investigated surfactant. 

This inherent nanomechanical versatility of AFM translates in the capacity to analyse not only hard, incompressible samples but also soft, compressible ones, such as biomolecules and cells. Moreover, the AFM has the capability to operate in air (i.e., no vacuum needed) and in liquid environments. This is very advantageous when compared with other high resolution techniques such as electron microscopy or optical techniques which operate in vacuum and need special sample preparation. Finally, the atomic scale reso-... 

The mass versus particle size distribution of several polymer latices with diameters in the range of 30 nm to 1500 nm was determined in less than 20 minutes using an integrated hydrodynamic chromatograph. Distributions obtained were compared with those found by other particle sizing techniques such as electron microscopy to verify validity of the technique. The instrument employed was able to analyze latices re-producibly with different optical properties, even though some of the injected particles may have been trapped within the column. Latex properties were correlated with particle size distribution data to illustrate the benefit of this particle sizing technique. 

Our previous work has shown that spin-coated films of zinc phthalocyanines exhibited detectable shifts in the optical absorption spectra during alcohol vapor exposure [5], We here report an investigation of the molecular interactions between zinc phthalocyanines and alcohols by the x-ray absorption spectroscopy, the phase contrast optical microscopy and the transmission electron microscopy. The experimental results are also compared with our Density Functional Theory (DFT) calculations of the interactions between alcohol molecules and the zinc atom of the phthalocyanines [5],... 

In addition, the crystal structures of both the racemic copolyamidc 11.7 and the cquimolccular mixture of the two configurationally homogeneous d- and i.-polyamides were studied and compared with that of optically pure 110.93 This study combined X-ray. electron microscopy, and 13C CP-MAS NMR measurements with computational methods. The two optically compensated and the optically pure polymers were shown to be highly crystalline systems the melting point of the racemic mixture was 250°C, considerably higher than those of the homopolymer (232°C) and the racemic polymer (226°C). The crystal structure of the racemic mixture could be... 

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