chemistry : reaction of nitrogen triodide?

Nitrogen triiodide, also called ammonium triiodide or nitrogen iodide, is a highly explosive compound of nitrogen and iodine, NI3. It is a contact explosive, and small quantities explode with a gunpowder-like snap when touched by even a feather, releasing a volatile cloud of iodine vapor. The decomposition of nitrogen triiodide occurs via the following reaction:

2NI3 (s) → N2 (g) + 3I2 (g)

Pure nitrogen triiodide is a dark red compound, first prepared in 1990 by reaction of boron nitride with iodine monofluoride in trichlorofluoromethane at -30°C.

The compound usually referred to as nitrogen triiodide is an ammonia adduct, NI3·NH3, synthesized by reacting iodine with ammonia. It was first prepared by Bernard Courtois in 1812, and its formula was finally determined unequivocally in 1905 by Silberrad.[1] Its solid state structure consists of zig-zag chains of corner-sharing NI4 tetrahedra, with ammonia molecules between the chains.

Small amounts of nitrogen triiodide are sometimes synthesized as a demonstration to high school chemistry students. However, because the compound is so unstable, it has not been used in blasting caps or primers for explosives. While still wet, nitrogen triiodide is safer to handle than the dry compound, but is still prone to spontaneous explosion. NI3·NH3 explosions leave orange-to-purple iodine stains that are difficult to wash. However, they can be easily removed by sodium thiosulfate solution. (wikipedia.com)

Nitrogen Iodide

Nitrogen Triiodide (NI3) has a very low activation energy, where it decomposes into Nitrogen gas and iodine, the solid element. The chain reaction is a consequence of the fact that it takes so little energy to start the reaction (touching it is enough).

I'm not sure what the mechanism would be.