Photochemical attachment of organic monolayers onto H-terminated Si(111): radical chain propagation observed via STM studies

Brian J Eves; Qiao-Yu Sun; Gregory P Lopinski; Han Zuilhof

doi:10.1021/ja045777x

Photochemical attachment of organic monolayers onto H-terminated Si(111): radical chain propagation observed via STM studies

J Am Chem Soc. 2004 Nov 10;126(44):14318-9. doi: 10.1021/ja045777x.

Authors

Brian J Eves¹, Qiao-Yu Sun, Gregory P Lopinski, Han Zuilhof

Affiliation

¹ Laboratory of Organic Chemistry, Wageningen University, Dreijenplein 8, 6703 HB Wageningen, The Netherlands.

PMID: 15521727
DOI: 10.1021/ja045777x

Abstract

Photochemical reactions of terminal alkenes with hydrogen-terminated silicon surfaces are being used by many groups to produce covalently attached organic monolayers with a wide range of terminal functionalities. Despite the considerable activity in this area, the mechanism for these reactions has not been definitively established. Here we present STM and HREELS data on a sequence of partially reacted samples, showing the progress of the reaction. The attachment reaction is found to proceed via formation of irregularly shaped islands that appear to grow by a pseudorandom walk process. These data support a radical chain propagation mechanism previously suggested for this reaction. However, since the photons employed here (447 nm) lack sufficient energy for Si-H bond cleavage, an alternate mechanism for initiating the chain reaction appears to be required.