Mechanistic study of the decomposition reactions of azobenzene

The electron impact‐induced fragmentation of azobenzenes and its d 1 , d 2 , d 5 , d 10 , and 15 N analogues was studied by mass Spectrometry and ion kinetic energy spectroscopy. The main fragment ions found in the mass spectrum of azobenzene are due to two parallel stepwise processes from the molecular ion: the expulsion of N 2 and two hydrogen radicals producing an ion at m / z 152 having possibly a biphenylene radical cation structure and loss of C 6 H 5 ⋅ and N 2 . Except in the elimination of two hydrogen atoms from [M − N 2 ] +· ions, hydrogen scrambling between the phenyl rings does not feature in azobenzene upon electron impact.