Chemical effects of photonuclear reactions in the propyl bromides

When nuclear reactions occur in atoms in molecules chemical changes follow as a reSult of the recoil of the product atoms. The nature of these ·chemical ·changes has been studied intensively for · a number of . systems but in most cases the . magnitude of the recoil energy has been about the same. In the present studies use was made of a much greater recoil energy than tha't normally used. The reaction Br( o , rn, )Br* gi)[es a recoil bromin~ a tom with an energy of the order o~ lO~ev, compared to 10 ev fbr the product of the Br(~, a )Br* reaction which is usually used. The chemical nature of the products resulting when the propyl bromides were irradiated with neutrons and 70-Mev gamma-rays was studied by established techniques. It is possible to differentiate between the reactions which occur while the recoiling bromine atom stili is highly energetic, or "hot 11 , and those which occur after it has been slowed down to thermal energies. The products of the hot reactions show little dependence on the initial recoil energy. In the case of the thermal reactions, the higher energy recoil produces a greater number of products which are different from the origina1 molecules. This can be attributed to the presence of a higher concentration of free radical fragments which are produced in slowing down the higher energy recoiling atom. These fragments combine with the radioactive bromine after it has reached thermal energies to form a greater variety an~ amount of ' new prbducts. +This report is based on a Ph. D. thesis by A. E. Richardson submitted December, 1956, to Iowa State College, Ames, Iowa. This work was done under contract with the Atomic Energy Cotnmission. ; •