Tetra-σ attachment of allyl cyanide on Si(111)-7×7

Abstract

The investigation of allyl cyanide adsorption on Si(111)-7×7 using high-resolution electron-energy-loss spectroscopy (HREELS), x-ray photoelectron spectroscopy (XPS), and ultraviolet photoelectron spectroscopy (UPS) reveals a tetra-σ binding mode through two [2 + 2]-like cycloaddition reactions. The HREELS spectra of chemisorbed monolayer show the absence of C = C, C = N, and C(sp2)-H stretching modes coupled with the appearance of C=N stretching mode at ∼1590 cm-1, demonstrating that both the C = C and C≡N of allyl cyanide directly participate in binding with the surface to form C - C and C = N bonds, respectively. This binding configuration was further confirmed in our XPS and UPS studies. The imine-containing skeleton formed on the surface can possibly be employed as a molecular template for a further modification of Si surfaces and syntheses in vacuum.