Study of photon stimulated ion desorption of methyl ester terminated self-assembled monolayer induced by carbon core excitation using Auger electron–photoion coincidence spectroscopy

Photon stimulated ion desorption of methyl ester terminated self-assembled monolayer induced by carbon core excitation was examined mainly using Auger electron–photoion coincidence (AEPICO) spectroscopy. The CHn+ (n=1–3) ion desorption is selectively observed at the excitation of carbon 1s to σ∗(O–CH3) anti-bonding orbital. AEPICO yield spectra at this resonant excitation showed CH3+ and CH2+ ion desorption are drastically enhanced at specific Auger electron energy. This enhancement is related to spectator Auger transition whose final state is that one electron is in an O–C anti-bonding orbital and two holes in O–C bonding orbitals. The results were compared with PMMA polymer thin film, which has the same methyl ester group at the side chain.