Our QMS measurements suggest that the Cp ligands are removed from the iron center and then further proceed to decompose in the plasma, generating C2H2 and C3H3 • . This is supported by OES, which shows emission lines of Fe I, C2, CH and possibly C3. The fragment CH is not possible to verify using the QMS, since the MS intensity contributions of CH can originate from the fragmentation patterns within the MS of various hydrocarbons.