Centrifugal exit barriers

It is clear, however, that the existence of such a point of no return is an approximation. Strictly speaking, it is only when the nascent prodncts are significantly separated from each other that we can be sure that they will indeed proceed along the exit vaUey to form stable products. Even so, everything that we know thus far supports the view that when there is a barrier along the reaction path, the location of the barrier, i.e., the saddle point, is the sensible choice for a point of no return. For reactions widiout an energy threshold, as we have seen in Section 3.2.6, the centrifugal barrier can be used to determine the location of the point of no return, which is identified with the maximum of the effective potential. 

The upper number is the total available energy the lower number, in parentheses, is < r> The < > for the SFq reactions have been adjusted to the higher DqCF-SFs). The reactions are thought to have only centrifugal barriers in the exit channel and — 0. Since A//°(complex) generally are not known, (E was omitted from this table. 

Table 2.19 lists some well-studied reactions that do not fit into the other classes of unimolecular reactions. Since the Ai/° (complex) values generally are not well known, the values cannot be assigned however, the values are small and the exit channel barriers are just the centrifugal barriers. Many of these reactions show osculating behavior for the appropriate range of... 

---