The formation of an enynic-like intermediate in diacetylene binding on Si(100)-2 × 1

Abstract

The covalent attachment of diacetylene (HC≡C-C≡CH) and the formation of a C=C-C≡C structure on Si(100) have 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 coexistence of ≡Csp-H and =Csp2-H stretching modes coupled with the concurrent observation of the C≡C and C=C stretching modes. The experimental results unambiguously demonstrate a [2 + 2]-like cycloaddition mechanism for diacetylene chemisorption on Si(100) through the binding between one of the C≡C groups and a Si dimer, consistent with the prediction of DFT calculations. © 2004 Elsevier B.V. All rights reserved.