Vibrational studies of the reactions of acetophenone with Si(1 0 0)-2 × 1

The covalent attachment of acetophenone on Si(1 0 0) has been investigated using high-resolution electron energy loss spectroscopy (HREELS) and density functional theory (DFT) calculations. The HREELS spectrum of the chemisorbed monolayer shows the absence of the CO stretching mode around 1687 cm−1 coupled with the retention of all vibrational signatures of a phenyl ring. The experimental results unambiguously demonstrate a [2 + 2]-like cycloaddition mechanism for acetophenone chemisorption on Si(1 0 0) through the binding between the CO group and a Si dimer, consistent with the prediction of DFT calculations.