Coexistence of ketenimine species and tetra-σ adduct at acetyl cyanide/Si(1 0 0)-2 × 1

The covalent binding of acetyl cyanide on Si(1 0 0)-2 × 1 has been investigated using high-resolution electron energy loss spectroscopy, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. The absence of the CO and CN stretching modes in the EELS spectra for chemisorbed molecules indicates the direct interactions between carbonyl, cyano groups and the dangling bonds on Si(1 0 0)-2 × 1. The characteristic CCN asymmetric stretching mode at 2031 cm−1 and CN stretching mode at 1667 cm−1 suggest the existence of both ketenimine species and tetra-σ adduct at the interface, further supported by XPS results and DFT calculations.