Abstract: Recently some new apparatuses have been developed to study the thermal decomposition and the photodecomposition mechanism of silver azide with some new experimental results. We anal ysed the experimental results with ab initio calculations (CASSCF, valence CI, MC-CEPA, ACPF and CEPA), assigned the spectrum structure of AgN₃, plotted the potential energy curves of AgN₃ and reinterpreted the photodecomposition mechanism of silver azide. The poten tial energy curves of the two lowest singlet and the two lowest triplet valence states of AgN₃ a long AgN-NN distance R2 show that the two singlet valence states are involved in the photodisso ciation of AgN₃, proved by the two peaks at 2.18 and 2.23 eV which are the results of the elec tron transition from the ground state to the two singlet valence states respectively.

Key words: Silver azide, Decomposition mechanism, Ab initio calculation