Reorientation criterion

A species can be considered as an INC if its lifetime is long enough to allow for other chemical reactions than the mere dissociation of the incipient particles. This is the minimum criterion that has to be fulfilled to term a reactive intermediate an ion-neutral complex, because otherwise any transition state would also represent an INC. [171,178] In addition, the reorientation criterion [29,169] should be met,... 

Morton, T.H. The Reorientation Criterion and Positive Ion-Neutral Complexes. Org. Mass Spectrom. 1992, 27, 353-368. 

Morton TH (1992) The reorientation criterion and positive ion- neutral complexes. Organic Mass Spectrometry 27 353- 368. 

Inequality (6.67) is the softest criterion of perturbation theory. Its physical meaning is straightforward the reorientation angle (2.30) should be small. Otherwise, a complete circle may be accomplished during the correlation time of angular momentum and the rotation may be considered to be quasi-free. Diffusional theory should not be extended to this situation. When it was nevertheless done [268], the results turned out to be qualitatively incorrect orientational relaxation time 19,2 remained finite for xj —> 00. In reality t0j2 tends to infinity in this limit [27, 269]. 

The Renaissance and Reformation brought about a gradual secularisation of natural philosophy during the 16th and 17th century, with the decline of religious conformity as a serious criterion for scientific validity, and with the reorientation of logical coherence to the explanation of new observations... 

As one can see the Frumkin model does not reflect all the details of the adsorption process. In some cases, the reorientation and aggregation models lead to better results. The scope of the data available is still insufficient to formulate a criterion for the best choice of the adsorption model. However, it follows from the results summarised in this chapter, that the reorientation model can be successfully applied to oxyethylated surfactants, and also for surfactants with relatively large molar area (o > 2.5T0 m /mol). At the same time, the surfactant molecules with relatively high values of the Frumkin constant and low molar area (m < 2.5-10 m /mol) are more capable for aggregation in the surface layer. 

It is not yet possible to establish a clear link between the approach of Ward and co-workers to the problem of molecular reorientation, which is discussed above at length, with many theories in the literature which take as their starting point the crystalline nature of the material. Some of these ideas have already been discussed in relation to the yield criterion for anisotropic polymers, but it is worth looking at them again to assess how they relate to the structure of the material which has been deformed in the... 

Following Streitwieser (13), we will call the type of effect illustrated in (1-6) a secondary isotope effect of the first kind, and those of (1-3) and (1-7) secondary isotope effects of the second kind, the criterion being whether or not bonds to isotopic atoms have undergone spatial reorientation. 

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