We reduced gas flow rate through the vent line from 2000 sccm to 1000 sccm resulting in a decrease in the base pressure from 3.2 kPa to 2.5 kPa, before adding a 2000 sccm of H2 through the reactor cell to give a process pressure of 5 kPa. The difference in elemental composition between the present and our previous study suggests that the change in gas flow velocity changes the deposition chemistry to favor deposition of films with more carbon and less hydrogen incorporation. We speculate that this can be due to lower purging rate of volatile reaction byproducts, leading to less dilution of active, unsaturated carbon-species in the deposition ambient. In the film deposited at 450 °C in Ar ambient, we observe a higher C-content, compared to hydrogen ambient with 25.5 at.% and 15.6 at.%, respectively. We suggest that this difference is due to the lack of hydrogen that restricts the decomposition route to solely β-hydride elimination. Such mechanism results in a higher concentration for C2H4 in the Ar ambient. The acetylene is more reactive byproduct compared to C2H6 formed in the hydrogen assisted ligand elimination of TEB .