13 N Species Formed by Proton Irradiation of Water

Abstract

We have shown that the irradiation of aerated water with 14.5-MeV protons produces as principal radioactive products nitrogen-13-labeled nitrate, nitrite, and ammonium ions. The yield of /sup 13/NH/sub 4//sup +/ varied from approximately 40% at low integrated dose (0.01 ..mu..Ah) to 0.4% at high integrated dose (25 ..mu..Ah), /sup 13/NO/sub 3//sup -/ varied from 50% at low dose to 85% at high dose. /sup 13/N/sub 2//sup -/ varied from 10% at low dose to 5% at high dose and 40% at intermediate doses. The results varied with recent use of target chamber. Induced radioactivity in the window foil was shown to have an effect on product composition. The effect of dissolved oxygen and certain additives (ethanol, ascorbic acid, formic acid, and ammonia) were investigated. In the absence of dissolved oxygen, or in the presence of ethanol, formic acid or ascorbic acid, almost pure /sup 13/NH/sub 3/ could be produced at doses up to 2..mu..Ah. The data are explained by postulating the initial production of /sup 13/NH/sub 3/ by successive abstraction of H atoms by the /sup 13/NH/sub 3/ to HNO/sub 2/ and HNO/sub 3/.