Comparison of n and s as Fall-Off Parameters in the Slater and Rice-Ramsperger-Kassel Classical Theories of Unimolecular Reaction

The classical Rice-Ramsperger-Kassel integral for the unimolecular rate constant has been evaluated over a range of s values at the several values of b = 32, 36, 40 and 44. Equivalent values of s and of the Slater theory parameter n have been found by comparison of the shape of the fall-off behavior predicted by both theories in the upper region of fall-off. The equivalence diverges from the limiting relation n = 2s—1 even below n = 8. The findings are discussed briefly.