Initial mechanisms for the decomposition of electronically excited energetic salts: TKX-50 and MAD-X1.

Decomposition of energetic salts TKX-50 and MAD-X1 (dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate and dihydroxylammonium 3,3′-dinitro-5,5′-bis-1,2,4-triazole-1,1′-diol, respectively), following electronic state excitation, is investigated both experimentally and theoretically. The NO and N2 molecules are observed as initial decomposition products from the two materials subsequent to UV excitation. Observed NO products are rotationally cold ( 1500 K). The vibrational temperature of the NO product from TKX-50 is (2600 ± 250) K, (1100 ± 250) K hotter than that produced from MAD-X1. Observed N2 products of these two species are both rotationally cold (<30 K). Initial decomposition mechanisms for these two electronically excited salts are explored at the complete active space self-consistent field (CASSCF) level. Potential energy surface calculations at the CASSCF(8,8)/6-31G(d) level illustrate that conical intersections play an essential role in the decomposition mechanisms. ...