Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Crystals selection and mounting

Under these conditions the first two lithium silylcuprates were isolated and structurally characterized. The complexes were found to be extremely air-and moisture-sensitive. During crystal selection and mounting the flask and the flushing argon were cooled down to ca. -50°C. At a temperature slightly above -30°C both compounds decompose instantaneously. [Pg.167]

During crystal structure analysis, the site occupancy factor (SOF) of each atom is ideally assigned a value imposed by the site symmetry of its position in the unit cell. For example, an atom located on a general position is assigned an SOF of one, while an atom situated on an inversion center has SOF = 0.5. However, it should be noted that the SOFs are lower than their symmetry-imposed values in cases where atoms are disordered. Furthermore, inclusion compounds such as solvates are often nonstoichiometric as they can lose solvent molecules during crystal selection and mounting. In such cases, it may then become necessary to model guest positions with lower than ideal SOFs. " ... [Pg.2195]

The diffraction from single crystals is certainly one of the most accurate techniques to obtain detailed information on the disposition of atoms in a solid. The crystals typically are very small ( 10 mm ), and they are selected and mounted in air on very small supports like glass fibers (or other amorphous and low absorbing... [Pg.46]

Sample Selection and Mounting. The sample should now be safe for a few minutes, and one can proceed to selection and mounting of a crystal. Selection of a suitable crystal is similar to procedures commonly used for chemically stable samples. A sowing needle held with a pin vice, and a sharp razor blade are useful tools. The binocular microscope should have a polarizing attachment to assist in judging quality of crystallinity. [Pg.260]

To fulfil the background requirements typical of rare event physics, particular care was dedicated to the selection and treatment of the materials used for the construction of CUORICINO the crystals where grown with low contamination materials in China and sent by ship to Italy where they have been optically polished with specially selected low-contamination powders. The mechanical structure of the array was made exclusively in OFHC copper and PTFE both these materials have an extremely low radioactive content. All the copper and PTFE parts of the mounting structure underwent a chemical treatment to remove any possible surface contamination. Finally, the array was assembled in an underground clean room in a N2 atmosphere to avoid Radon contamination. [Pg.365]

Carefully selected crystals from both experiments, with regular prismatic shapes (all dimensions are within 0.4 to 0.6 mm) were glued on glass fibers and mounted on a Stoe reciprocal lattice explorer camera. Zr filtered molybdenum Ka radiation was used. [Pg.57]

Crystallization, experimental methods overview, 1, 207 Crystal mounting, experimental methods overview, 1, 209 Crystal selection, experimental methods overview, 1, 209 CSA, and apparent dynamic NMR, 1, 423 CSD, see Cambridge Structural Database C2-symmetric metallocenes, for polypropylene polymerization, 4, 1058 CT transitions, see Charge-transfer transitions Cubanes... [Pg.87]

Under the microscope a crystal with desirable attributes (size, apparent crystallinity) is selected and cleaned. The crystal is then removed from the oil by lifting it out with a prepared mounting fiber (see below for description), and immediately transferred to the cold stream on the diffractometer. This step can often be simplified if the crystal is moved toward the surface of the oil before one attempts to pick it up. [Pg.260]


See other pages where Crystals selection and mounting is mentioned: [Pg.105]    [Pg.308]    [Pg.7]    [Pg.15]    [Pg.197]    [Pg.209]    [Pg.105]    [Pg.308]    [Pg.7]    [Pg.15]    [Pg.197]    [Pg.209]    [Pg.38]    [Pg.98]    [Pg.580]    [Pg.199]    [Pg.209]    [Pg.300]    [Pg.17]    [Pg.151]    [Pg.61]    [Pg.67]    [Pg.264]    [Pg.400]    [Pg.193]    [Pg.650]    [Pg.207]    [Pg.400]    [Pg.309]    [Pg.261]    [Pg.25]    [Pg.1028]    [Pg.402]    [Pg.336]    [Pg.193]    [Pg.3223]    [Pg.538]    [Pg.65]    [Pg.180]    [Pg.145]    [Pg.86]    [Pg.470]    [Pg.337]    [Pg.395]    [Pg.9]    [Pg.175]    [Pg.19]   
See also in sourсe #XX -- [ Pg.15 , Pg.16 ]




SEARCH



Crystal selecting

Crystallization selection

Crystallization selective

Mount

© 2024 chempedia.info