After verifying PO's stability and detectability, its formation mechanism still needs to be clarified. With PC as the educt, one could imagine several possible reaction pathways leading to the formation of PO. Figure shows a comparison between the assumed most relevant decomposition products for the PO formation. [CO 3 ] -2 and propandiolate are found to chemisorb on all sodium and the (111) sodium chloride surface, which is probably the cause that they are invisible for the experimental gas phase analysis. Based on the experimental GC results, in which we did not detect any CO 2 , and our adsorption calculations, which suggest that any CO 2 that is formed should be detectable, we can assume that no CO 2 is involved in the PO reaction, while CO is abundant. Our previous computational study identified a CO-producing decomposition reaction in which PC would decompose into propandiolate and CO. CO was readily detected within the GC experiments while propandiolate chemisorbs The dissociation of CO into oxygen and elemental carbon has been previously observed .