Transmission electron microscopy ultrasonic

Temperature programmed desorption Thermal analysis Thermodynamic analysis Transmission electron microscopy ultrasonic measurements X-ray diffraction... 

High resolution transmission electron microscopy (HRTEM) micrographies were performed with a JEOL JEM-3010 microscope operating at 300 kV (Cs= 0.6 mm, point resolution 1.7 A). Images were recorded with CCD camera (MultiScan model 794, Gatan, 1024 x 1024 pixels, pixel size 24 x 24 pm2). The powder samples were mixed in ethanol and then ultrasonicated for 10 min. A drop of the wet sample was placed on a copper grid and then allowed to dry for 10 min before TEM analysis. 

The dispersions were obtained by emulsification via ultrasonication of a toluene solution of the unsaturated homopolymer in an aqueous surfactant solution. This was followed by exhaustive hydrogenation with Wilkinson s catalyst at 60°C and 80 bar H2 to produce a dispersion with an average particle size of 35 nm (dynamic light scattering and transmission electron microscopy analyses). The same a,co-diene was used as comonomer in the ADMET polymerization of a phosphorus-based monomer, also containing two 10-undecenoic acid moieties... 

Figure 4. Inhomogeneity of silica-aluminas prepared by various methods. A series of 17 commercial samples of silica-aluminas from seven different producers was submitted to microanalysis. All of them showed considerable fluctuations of composition at the scale of several tens of nanometers to several micrometers. These samples were prepared by coprecipitation or by the sol-gel method. It is not known whether some of these samples were prepared from alkoxides. Smaller but significant fluctuations at the micrometer scale were also observed for two laboratory samples prepared from alkoxides. The samples were dispersed in water with an ultrasonic vibrator. A drop of the resulting suspension was deposited on a thin carbon film supported on a standard copper grid. After drying, the samples were observed and analyzed by transmission electron microscopy (TEM) on a JEOL-JEM 100C TEMSCAN equiped with a KEVEX energy dispersive spectrometer for electron probe microanalysis (EPM A). The accelerating potential used was 100 kV.

Figure 1. Transmission electron microscopy (TEM) images and selected area electron diffraction pattern (SAED) of preformed gold nanopaiticles before and after ultrasonic treatment A), C) and E) TEM images of gold nanopaiticles bef e soiication, after 20 rain and 45 min of ultrasonic treatment, respectively. B), D) and F) SAED patterns (camera length 360 nm) of gold nanopaiticles before ultrasonic treatment and after sonication for 20 min and 45 min respectively.

Transmission electron microscopy was performed with a Philips EM420 and a Philips CM200 equipped with a field-emission gun and an EDAX detector for elemental analysis. Ground and ultrasonically dispersed (in dry -hexane) samples were brought on copper grids covered by a thin polymer film on which carbon was deposited. 

The adherence of small particles of precious metals to the surface of the support can be assessed by transmission electron microscopy. It has been observed that mild ultrasonic treatment of the catalyst in a liquid, such as ethanol, can remove precious metal particles from the surface of the support. After applying a drop of the suspension resulting from the ultrasonic treatment on the carbon films used as specimen support the precious metal particles released from the support show up on the carbon support film. Especially dark-field techniques are useful to indicate the presence of precious metal particles on the carbon support film. 

The size of nanoparticles was determined by transmission electron microscopy (TEM) using a JEOL JEM-100B. Samples were dispersed in the solvent using an ultrasonic oscillator. A drop of solution was sputtered onto an amorphous carbon film deposited on a copper grid. After evaporation of the liquid, the samples were placed into the microscope. X-Ray diffraction (XRD) measurements were made for powder samples with a DRON-3 diffractometer (CuKa radiation, X= 1.54056 A). 

Many techniques have been developed to measure the Young s modulus and the stress of the mesoscopic systems [12, 13]. Besides the traditional Vickers microhardness test, techniques mostly used for nanostructures are tensile test using an atomic force microscope (AFM) cantilever, a nanotensile tester, a transmission electron microscopy (TEM)-based tensile tester, an AFM nanoindenter, an AFM three-point bending tester, an AFM wire free-end displacement tester, an AFM elastic-plastic indentation tester, and a nanoindentation tester. Surface acoustic waves (SAWs), ultrasonic waves, atomic force acoustic microscopy (AFAM), and electric field-induced oscillations in AFM and in TEM are also used. Comparatively, the methods of SAWs, ultrasonic waves, field-induced oscillations, and an AFAM could minimize the artifacts because of their nondestructive nature though these techniques collect statistic information from responses of all the chemical bonds involved [14]. 

The particle size and distribution of the samples were analyzed by transmission electron microscopy (TEM) (Tecnai G220 S-Twin, 200 kV). Powder samples were ultrasonicated in ethanol and dispersed on copper grids covered with a porous carbon film. Energy dispersive X-ray spectroscopy was also performed in the same microscopy. 

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