Alkyl monolayers anchored to Si(111) were prepared in diluted and neat I-alkene by thermal reaction. Monolayers prepared were investigated by attenuated total reflectance infrared spectroscopy. It was found that alkyl chains in the monolayers anchored to Si(111) had an all-trans conformation. Monolayers prepared in diluted l-alkene were identical with that prepared in neat I -alkene. The rate of reaction between l-alkene and hydrogen-terminated silicon remarkably depended on the concentration of l-alkene. (c) 2005 Elsevier B.V. All rights reserved.