Reaction rate for isomerization in a molecular beam

Abstract

It is shown that in an ideal gas (molecular beam), at temperature T, consisting of molecules that can isomerize and whose molecular dynamics can be non-ergodic, the observed decay rate of the concentration can be greater than that. k TST, predicted by transition state theory. The “observed” rate constant is then given by ( Q/ Q ≠ (1)) k TST where Q ≠ (1) is the contribution to the canonical partition function Q arising from only activated and irregular states. It is also shown that in the presence of strong collisions the long-time decay rate of the concentration provides no information about the intramolecular rate process, but at low collision rates it is sensitive to the non-ergodic dynamics.