Two techniques have been utilized to reveal the vaporization chemistry of two organoaluminum precursors to aluminum nitride, trimethylaluminum ammonia (compound I) and trimethylamine alane (compound II). Molecular beam mass spectrometry and time-of-flight of a modulated molecular beam have been used together to discover, first, the fragmentation patterns of each precursor and then, second, determine the species that generated those fragments. Time-of-flight analysis has provided information that could not be obtained by mass spectrometry alone. It was determined that compound I undergoes a continuous decomposition at room temperature to produce monomer, (CH3)2AlNH2, methane, CH4, and oligomers of the monomer,trimer, [(CH3)2AlNH2]3, and dimer, [(CH3)2AlNH2]2. Compound II decomposes continuously at room temperature to produce N(CH3)3. Compound II was also found to decompose on the metal surfaces of the inlet system, specifically the pulse valve when it was operating at higher temperatures.