Differential Energy-Distributions In Nonthermal Systems - Model-Calculations And Applications To F-18 For-F Nuclear Recoil Substitutions In Ch3cf3

A general method has been developed for the determination of the differential energy distribution in nonthermally activated reacting systems. A series of known distributions and kinetic models has been used to test this method and to determine its efficacy. Application was then made to the kinetic data of energetic CH3CF218F formed by the substitution of F by 18F produced by nuclear recoil. The distribution obtained for this activated CH3CF218F is seen to be highly energetic with a median energy of 137.6 kcal mol−1 and with 33.1% of the molecules possessing energy in excess of 171 kcal mol−1. The shape of the calculated distribution suggests that there are two mechanisms for the formation of CH3CF218F from CH3CF3 and 18F, as well as that 62 kcal mol−1 is a lower limit to the kinetic energy needed by the 18F atom for this substitution to take place.