According to various authors, the value of the yield of the solvated electron in the pulse radiolysis of hexamethylphosphorotriamide (HMPT) varies from 1.2 to 2.4 and increases to 4.2 or 3.1 in the presence of NaBr. We exposed this compound to γ rays after purification and saturation with N 2 O. N 2 was formed with a yield G(N 2 ) = 4.4 ± 0.4. After elimination of a certain number of processes which might also lead to N 2 formation, it was concluded that this G(N 2 ) corresponds to the total yield of electrons. This value was confirmed by measuring G(Br − ) obtained by radiolysis of HMPT with p-bromophenol as a scavenger. The yield of N 2 remains constant whenever solutes generally known as good electron scavengers are added (H + , CH 3 COCH 3 , NO 3 − ). An interpretation of the results leads to the suggestion of the formation of a dielectron in this medium.
