Clusters migration

Seki, T., Namba, T., Mochizuki, H., and Onodera, M. (2007). Clustering, migration, and neurite formation of neural precursor cells in the adult rat hippocampus.. Comp. Neurol. 502, 275-290. 

Fig. 8. Sodalite and hexagonal prism site I and II cation locations in Ag/faujasites. Configuration (a) shows the normal cation locations with occupied sites at SI, SI and SII. Configuration (b) shows cation sites that have resulted from cation and/or cluster migration upon vacuum thermal treatment. This configuration shows occupied sites at SI, SII, and SII (Hutson and Yang, 2000).

Other types of information which can be obtained using EELS are oxidation state, coordination number, and cluster size of heavier atomic number elements (25). Applicability and feasibility is just starting to be demonstrated. There are many problems associated with trying to obtain useful quantitative information on small volumes of catalyst. The major concern is radiation damage. Others include, contamination, sample preparation, beam reactivity (especially crucial for redox information), cluster migration and redispersion, support reactivity with the catalyst metals, and desorption of some elements under high vacuum. 

---