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.
- silicon surfaces
- alkyl monolayers
Eves, B. J., Sun, Q. Y., Lopinski, G. P., & Zuilhof, H. (2004). Photochemical attachment of organic monolayers onto H-terminated Si(111): Radical chain propagation observed via STM studies. Journal of the American Chemical Society, 126(44), 14318-14319. https://doi.org/10.1021/ja045777x