The dissociative adsorption of unsaturated alcohols on Si(111)-7x7

• Published in: Surface science 2008-08, Vol.602 (15), p.2647-2657
• Main Authors: Tang, Hai Hua, Dai, Yu Jing, Shao, Yan Xia, Ning, Yue Sheng, Huang, Jing Yan, Lai, Yee Hing, Peng, Bo, Huang, Wei, Xu, Guo Qin
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Physics
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2008.06.019

High-resolution electron energy loss spectroscopy (HREELS), X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations were used to investigate the attachment of allyl and propargyl alcohols on Si(1 1 1)-7X7 under ultra-high vacuum conditions. The HREELS spectra of chemisorbed allyl alcohol (AA) show the concurrent appearance of characteristic stretching vibrations of Si-H (2104 cm-1) and Si-O (795 cm-1) coupled with the retention of vibrational features of CC stretching (1657 cm-1) and (sp2)C-H stretching (3012 and 3102 cm-1). These results clearly demonstrate the dissociative reaction nature via the hydroxyl group for the chemisorption of AA on Si(1 1 1)-7X7, which was further supported by XPS and DFT studies. A similar reaction pathway was found for propargyl alcohol (PA) adsorbed on the same Si(1 1 1)-7X7 surface. Our studies suggest that OH dissociation is highly favorable compared to [2+2]-like cycloadditions via CC/CC for organic reactions on silicon surfaces, which may be explained by the large spatial separation between the adjacent adatom-rest atom pair on Si(1 1 1)-7X7.