Based on the mass spectrometry measurements, where a very sharp m/z = 16 signal was observed during each NH3 pulse for both the plasma and thermal processes (Fig. ), the reaction mechanism for the interaction between NH3 and the -Al(CH3)x covered surface produces methane. Therefore, we suggest that ammonia molecules, or possibly NHx species in the plasma process, undergo a ligand exchange with surface-bound Al centers to eliminate methane and form an Al-N bond. During the co-reactant half-cycle with NH3, the continued, and even higher intensity compared to that during the TMA pulse, detection of CH4 + ions reaching the mass spectrometer, suggests that more methane is produced in the NH3 pulse than in the TMA pulse.