title: Dry synthesis of triple cumulative double bonds (C=C=C=N) on Si(111)-7 x 7 surfaces.
abstract: The interactions of cyanoacetylene and diacetylene with a Si(111)-7 x 7 surface have been studied as model systems to mechanistically understand the chemical binding of unsaturated organic molecules to diradical-like silicon dangling bonds. Vibrational studies show that cyanoacetylene mainly binds to the surface through a diradical reaction involving both cyano and C[triple bond]C groups with an adjacent adatom-rest atom pair at 110 K, resulting in an intermediate containing triple cumulative double bonds (C=C=C=N). On the other hand, diacetylene was shown to the covalently attached to Si(111)-7 x 7 only through one of its C[triple bond]C groups, forming an enynic-like structure with a C=C-C[triple bond]C skeleton. These chemisorbed species containing triple cumulative double bonds (C=C=C=N) and C=C-C[triple bond]C may be employed as precursors (or templates) for further construction of bilayer organic films on the semiconductor surfaces.
authors.affiliation: Department of Chemistry, National University of Singapore, 10 Kent Ridge, Singapore 119260.
authors.forename: Hai Gou
authors.initials: HG
authors.lastname: Huang
authors.forename: Chao Li
authors.initials: CL
authors.lastname: Xiang
authors.forename: Yue Sheng
authors.initials: YS
authors.lastname: Ning
authors.forename: Jing Yan
authors.initials: JY
authors.lastname: Huang
authors.forename: Siau Gek
authors.initials: SG
authors.lastname: Ang
authors.forename: Guo Qin
authors.initials: GQ
authors.lastname: Xu