PHOTOFRAGMENTATION OF THE CORE-EXCITED S-TETRAZINE MOLECULE NEAR THE CARBON AND NITROGEN K-EDGES

Total photoionization spectra of s-tetrazine have been measured with soft X-ray synchrotron radiation, in the vicinity of the nitrogen and carbon 1s edges. Multicoincidence time of flight mass spectrometry measurements show that the core-excited or -ionized molecule undergoes a cascade of dissociative double and triple ionization, causing the formation of numerous atomic and diatomic ionic and neutral fragments including N-2 and HCN. Several routes leading to two-, three-, and many-body dissociation reactions with the CN2H+, C2N3H22+, and C2N2H22+ intermediates are discussed. The results are consistent with the formation of a wide electron energy distribution and significant internal energy in the residual ion and nascent primary fragments. The role of multistep dissociative autoionization in the single-, double-, and triple-ionization continua is discussed, including the statistical dissociation of intermediate ion fragments. The absence of site selectivity is discussed in terms of charge delocalization, symmetry considerations, efficiency of the multifragmentation, and possible statistical fragmentation steps.