Ene-like Reaction of Cyclopentene on Si(001)-2 × 1: An XPS and NEXAFS Study

• Published in: Journal of physical chemistry. C Vol. 116; no. 23; pp. 12680 - 12686
• Main Authors: Khaliq, Anzar, Pierucci, Debora, Tissot, Héloïse, Gallet, Jean-Jacques, Bournel, Fabrice, Rochet, François, Silly, Mathieu, Sirotti, Fausto
• Format: Journal Article
• Language: English
• Published: American Chemical Society 14.06.2012
• Subjects: Chemical Sciences
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp302952m

The control and the understanding of single-molecule covalent coatings on silicon surfaces is increasingly important in designing nanoscale electrical elements, such as organic/inorganic semiconductor hybrid structures. In this respect, ordered arrays of cyclopentene deposited on Si(001)-2 × 1 appear as promising buffer layers for further molecular crystal growth on the substrate. In this work, we examine the adsorption of cyclopentene on Si(001)-2 × 1 at 130 and 280 °C by means of C 1s XPS and NEXAFS. Until now cryogenic and room-temperature adsorption studies tended to prove that cyclopentene adsorption results from a formal cycloaddition ([2 + 2]-like) reaction of the CC double bond with a silicon dimer. Our XPS/NEXAFS study reveals that an ene-like reaction competes with the [2 + 2]-like reaction channel, leading to the formation of products bearing a CC bond, already at deposition temperature as low as ∼130 °C. This work helps to determine the optimum conditions leading to optimal chemical order in view of applications of cyclopentene as a buffer layer.