Transmission electron microscopy comparison with other

The expression for AEg (eq. 5.4) has often been nsed to calcnlate the size of small semicondnctor particnlates for comparison with sizes measnred by transmission electron microscopy. Expression 5.4 works well for particles of diameter above -50 A (see e.g. Serpone et al., 1995a). The reasonable congmence notwithstanding, there are other plausible explanations for the observed bine shifts in the bandgap. Studies by Serpone and co-workers (1995a, 1995b) contended that the earlier reports of bine-shifted absorption thresholds, taken as evidence for Q-size effects in small Ti02 particles, may in fact be direct (Franck-Condon) electron transitions in an otherwise indirect-gap semiconductor. 

Figure 936 Scanning electron microscopy image of other acrylonitrile-butadiene-styrene terpolymer after the sorption stage - insert figure comparison with transmission electron microscopy image of unfoamed sample at same magnification.

The MS analysis of 2 also revealed the formation of dimers, trimers, and other oligomers, suggesting that Coig-calixarenes have a strong propensity to coalesce into well-defined nanoclusters (Fig. 34.4a). This indeed proved to be the case Solutions of 2 in hot 0-dichlorobenzene (ODCB) produced Co nanocrystals with narrow size distributions, based on transmission electron microscopy (TEM) analysis (2.9 0.4 nm or 3.6 0.4 nm Fig. 34.4b, c) similar results were obtained for solutions of 1. These NP size distributions were constant over time by comparison, the thermolysis of PhOCH2C = CH-Co2(CO)g 3 (the monovalent equivalent of 1) yielded Co NPs whose mean size slowly increased over time (Fig. 34.4d). These studies confirmed that the calixarene-encapsulated Co NPs were thermally stable and resistant to digestive ripening. 

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