The thermal decomposition of nitrate esters mainly yields the gases molecular nitrogen (N) and carbon dioxide. The considerable chemical energy of the detonation is due to the high strength of the bond in molecular nitrogen.  This stoichiometry is illustrated by the equation for the detonation of nitroglycerin.
Illustrative of the highly sensitive nature of some organic nitrates is Si(CHONO). A single crystal of this compound detonates even upon contact with a teflon spatula and in fact made full characterization impossible. Another contributor to its exothermic decomposition (inferred from much safer in silico experimentation) is the ability of silicon in its crystal phase to coordinate to two oxygen nitrito groups in addition to regular coordination to the four carbon atoms. This additional coordination would make formation of silicon dioxide (one of the decomposition products) more facile.