Nickel transmission measurements

The nickel single crystal(MARZ grade 99.995%, supplied by MRC) was metallographically polished down to 1 pm diamond paste, then chemically polished as described by Graham and Cohen (15). Transmission x-ray diffraction measurements confirmed the (100) direction of. the face to 0,0.5°. The specimen, of area o>2 cm2, was spot-welded to a nickel rod fastened to the specimen manipulator. It could be heated by electron bombardment or radiativity and cooled to vloO K through the nickel rod and a LN -cooled copper braid. A control unit held the crystal temperature (via a chromel-alumel thermocouple spot-welded to the back of the crystal) constant to within 1 K. 

The results that have been obtained with the catalysts after reduction and passivation are the same as those after calcination, i.e. the textural and structural properties of the support material have completely been retained after the treatments (as determined with nitrogen physisorption. X-ray diflfiaction and transmission electron microscopy). Information concerning the metallic nickel particles has been obtained with X-ray diffraction and transmission electron microscopy. Diflractograms of the catalysts after passivation are shown in Fig. 8. The observed features are exactly the same as for the oxidic systems (Fig. 4) only very broad and low diffractions are visible for the catalyst ex citrate, whereas sharp, intense peaks with a broad onset are observed for the catalyst ex nitrate. Consequently the nickel particles of the catalyst ex citrate have resisted sintering during the reduction treatment, thereby conserving the high dispersion of the catalyst. These results were confirmed by transmission electron microscopy measurements (not shown) only very small nickel nanoparticles situated inside the mesopores were found for the catalyst ex citrate. 

One method used to isolate a X-ray line from unwanted background and noise, employs equilibrated filters. It consists of linking the concentration of interest to the difference between two measurements. The first is obtained by installing a transmission filter between the sample and the detector to isolate the characteristic radiation of the element wanted and the second by fitting an absorption filter which is opaque to this same radiation. This will enable, for example, to quantify the copper from its main spectral line by using two filters, one made of nickel and the other made of cobalt. The fluorescence originating from the filters themselves is a limiting factor in this method, which is reserved for routine measurements. 

Carbon deposits formed by exposure to hydrocarbons and carbon monoxide exhibit, depending primarily on the temperature during deposition, seven reactive carbon states during TPSR with 1-atm Ho, including two very reactive states of chemisorbed carbon, a carbon film, nickel carbide, and two types of filamentary carbon. Filamentary carbon was identified by transmission and scanning electron microscopy, and Nl C was identified from x-ray diffraction measurements. 

Powder morphology was investigated using a transmission electron microscope (TEM, Model JEM-IOOCXII). Crystallite size of the powders and grain size of Nd YAG ceramics calcined at different temperatures were calculaied by X-ray diffraction (XRD, model D/maxrA, using nickel-filtered Cu-Ka radiation) patterns from the Scherrer s equation. Microstructures of the fractured and the thermal etched mirror-polished surfaces of Nd YAG specimens were observed by scanning electron microscopy (SEM, Model S-4800). Densities of the samples were measured by the Archimedes draining method. 

Digest sample with acid mixtures remove method sulfide, nickel and cobalt add dithiozone and CCI4 measure transmission at 540 nm... 

Salt purity, density, chemical composition, and other properties. In the laboratory, high-temperature salt properties are measured by spectroscopy. Laser or other light is sent through the salt, and the transmission of the light is measured as a function of frequency. In more sophisticated systems, secondary emission lines are measured. Salt impurities that can be measured to very low concentrations include uranium, the actinides, iron, chromium, and nickel. The chemical valence state can also be measured. This is likely to be the preferred method for monitoring the concentration of impurities and the redox potential of the salt and thus the performance of the salt cleanup systems. It would be the equivalent of the instrumentation used to monitor water chemistry in an LWR. 

The nickel particle sizes were measured from electron micrographs obtained with a Transmission Electron Microscope (TEM, JEOL lOOCXII UHR). The average particle... 

Electron transmission spectra of bis-(ri3-allyl) complexes of nickel, palladium and platinum have been reported. Each compound displayed three resonances associated with electron capture into three empty n ligand MO s. The measured electron attachment energies... 

Specific surface areas were measured by the BET method with adsorption of nitrogen at 77 K. A JEOL JSM-T200 scanning electron microscope (SEM), a JEOL JEM-2000EX transmission electron microscope (TEM) and a Rigaku Denki powder X-ray diffractometer with nickel filtered CuKoC radiation were used for characterization of the samples. 

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