title: Selective attachment of benzaldehyde on Si(100)-2 x 1: structure, selectivity, and mechanism.
abstract: The interaction of benzaldehyde with the Si(100) surface has been investigated as a model system for understanding the interaction of conjugated pi-electron systems with semiconductor surfaces. Vibrational features of chemisorbed benzaldehyde unambiguously demonstrate that the carbonyl group directly interacts with the Si surface dangling bonds, evidenced in the disappearance of the C=O stretching mode around 1713 cm(-1) coupled with the retention of all vibrational signatures of its phenyl ring. X-ray photoemission spectroscopy shows that both C 1s and O 1s binding energies of the carbonyl group display large downshifts by 1.9 and 1.3 eV, respectively. Vibrational and electronic results show that the covalent attachment of benzaldehyde on Si(100) occurs in a highly selective manner through the direct interaction of both C and O atoms of the carbonyl group with a Si=Si dimer to form a four-membered Si-C-O-Si ring at the interface, leaving a nearly unperturbed phenyl ring protruding into vacuum. This conclusion is further confirmed by the observation of a predominant protrusion for benzaldehyde adsorbed on Si(100)-2 x 1 in scanning tunneling microscopy experiments, consistent with the predication of density-functional theory calculation.
authors.affiliation: Department of Chemistry, National University of Singapore.
authors.forename: Hai Gou
authors.initials: HG
authors.lastname: Huang
authors.forename: Yong Ping
authors.initials: YP
authors.lastname: Zhang
authors.forename: Ying Hui
authors.initials: YH
authors.lastname: Cai
authors.forename: Jing Yan
authors.initials: JY
authors.lastname: Huang
authors.forename: Kian Soon
authors.initials: KS
authors.lastname: Yong
authors.forename: Guo Qin
authors.initials: GQ
authors.lastname: Xu