SEARCH FOR PERFECTLY ORDERED DENSE MONOLAYERS

We present some basic criteria to obtain well-ordered Langmuir monolay ers and of high surface densities. The fluorinated molecules such as C 10F21CH2COOH and C11F23COOH appear as good candidates to fulfil these requirements. Independent, grazing incidence X-ray diffraction and sur face pressure isotherm measurements give an advantage to the first mol ecule. This may have some important practical applications in the surf ace modification of solid substrates (e.g. silicon wafers) by thin org anic layers. Assuming that a water film is present on the solid substr ate prior to deposition, the above comments on Langmuir monolayers str ongly suggest that fluorinated silanes should form optimum grafted lay ers.