Distribution homogeneity sampling considerations

For samples photolyzed on ZSM-5 zeolite, the product distributions of 31 and 32 are dramatically different from those photolyzed in homogeneous solutions. First, the rearrangement products were totally suppressed. Second, diphenylethane 39 resulted from coupling of benzyl radical was not found. Only phenol 38 and toluene were detected. In contrast, photolyses of 33 and 34 on ZSM-5 follow strikingly different pathways. Both photo-Fries rearrangement 36 and 37 and decarbonylation products 35 and 39 were formed. These results can be understood from consideration of size- and shape-selective sorption combined with restriction on the mobility of the substrates and reaction intermediates imposed by the pentasil pore system. 

Theoretical models for the dieleetrie properties of heterogeneous mixtures [for instance, Eq. (20), or extensions of this model] are commonly applied in order to explain or predict the dieleetrie behavior also of emulsions (106, 158). However, in the present theories a homogeneous distribution of the dispersed phase is required. This requirement is rarely fulfilled in a real emulsion system where the inherent instability makes the emulsions go through different stages on the way towards complete phase separation. Proeesses like sedimentation, flocculation, and coalescence continuously alter the state of the system (Fig. 36). These processes also influence the dielectric properties (159—162). Thus, the dielectric properties of one given sample may vary considerably over a period of time (160), depending on the emulsion rate. 

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