The dissociative adsorption of unsaturated alcohols on Si(1 1 1)-7×7

• 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: Alcohols; Chemisorption; Density functional calculations; Electron energy loss spectroscopy (EELS); Physical adsorption; Silicon; Surface chemical reaction; X-ray photoelectron spectroscopy
• 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)-7×7 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 C C stretching (1657 cm −1) and (sp 2)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)-7×7, 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)-7×7 surface. Our studies suggest that OH dissociation is highly favorable compared to [2+2]-like cycloadditions via C C/C C 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)-7×7.