Vacuum transfer system, extended

In most microscopy studies the catalyst is examined under vacuum. To understand the system, the catalyst should be examined under reactor conditions. Environmental chambers that do not reduce instrument resolution are presently not available. Similarly, pretreatment systems attached to the instrument would extend characterization insight. At the very least, sample delivery systems that minimize air exposure are necessary. For example, air exposure during sample transfer as might occur with a reduced Pd catalyst can alter the crystallite morphology. Such studies would be expected to enhance catalyst development. 

The metal reduction of the polycyclic system is usually carried out in an ether solvent and by an alkali metal at low temperature (—78 °C). When potassium metal is applied it is best to prepare a metal mirror. Sodium and lithium react, either directly in the form of a metal wire, or after treatment in an induction furnace. Cesium is prepared by thermolysis of cesium azide. It has recently been found that the application of an ultrasonic bath facilitates the reaction and avoids side reactions. The reaction can be carried out in a modified NMR tube or in an ESR cavity. Diamagnetic ions are prepared in extended NMR tubes to which the metal is extruded and sealed under vacuum. Reaction rates are difficult to compare as the electron-transfer process depends on various experimental conditions such as concentration, temperature, the presence of impurities, the solvent and the nature of the metal surface. It may take from minutes to days to form the first radical-anion the second step then follows and can sometimes be rather slow 10 13). 

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