The structures and decomposition reactions of doubly charged phenylenediamines were studied by means of charge separation (CS) and electron capture induced decomposition (ECID)spectra. The deisomerization of the threeisomers is prior to the metastable decompositions of doubly charged ions. Several different structures of transition states were postulated by measuring the translational energy releases of different charge separation channels of the doubly charged ions. The proudct ions of charge separation are also dominated in the ECID spectra, However the ECIC spectrum is obviously a reliable method to differentiate the three isomers which are difficut to be distinguished using the normal mass spectrometric methods.

Key words: ISOMER, BENZENEDIAMINE, DOUBLE-CHARGE ION