A tracer study of the reactions promoted by the decay of a tritium atom contained in the molecule of ethane

Abstract

The chemical fate of tritiated ethane molecule following the decay of the radioactive atom has been studied with a tracer technique, [1,2-³H₂]ethane being allowed to decay in gaseous systems at atmospheric pressure.

From the analysis of the tritiated decay products, account being taken of the available information on the primary ions resulting from the decay of C₂H₅T at low pressure and the ion–molecule reactions occurring in the system investigated, a detailed picture of the chemical processes following the nuclear transition has been obtained.

In particular, the results are consistent with the hypothesis that the decay-induced fragmentation of the ethane molecule is largely independent of pressure. The labelled ethyl ions formed in about 80% of the β-transitions undergo a hydride-ion transfer reaction with the inactive ethane molecules, while the labelled products other than ethane originate from the fragmentation processes that take place in about 20% of the decay events and from the reactions of the fragment ions.

The satisfactory agreement between the experimental yields of the labelled decay products and those expected from the current knowledge on ion–molecule reactions in the systems investigated confirms that the decay of suitably labelled molecules can afford a useful tool for the study of the ion–molecule reactions in systems at atmospheric pressure.