Fluoroalkylsilane (FAS) self-assembled monolayers were prepared on silicon oxide surfaces by exposing the oxide surfaces to vapor of an FAS precursor, that is, [CF3(CF2)(n)(CH2)(2)Si(OCH3)(3), n = 5 or 7, referred to as FAS13 or FAS17, respectively] and were studied by lateral force microscopy (LFM). The water-contact angles of these FAS 13 and FAS 17 monolayers were similar to 106degrees and 112degrees, respectively. LFM values for the FAS 13 monolayer were found to be slightly greater than that on the FAS 17 monolayer. CF3/CF2 ratios of the monolayers measured by x-ray photoelectron spectroscopy suggest that a surface CF3 density of the FAS 17 monolayer was greater than that of the FAS13 monolayer. These results indicates that the FAS13 monolayer has a molecular assembled structure more disordered than that of the FAS17.