A NEW OPTICAL-FIBER SENSOR FOR MEASURING SURFACE PRESSURE OF LANGMUIRMONOLAYERS

The surface pressure of Langmuir monolayers can be measured by a Langm uir balance or Wilhelmy plate. However, both of these sensors have a l ong contact length with the monolayer, normally longer than 10 mm. An optical-fiber sensor has been developed for the measurement of the sur face pressure of monolayers. It has a short contact length with the mo nolayer, less than 250 mu m, while the sensitivity of this method is s till very high. Thus, the new sensor presents a small disturbance to t he monolayer and is very suitable for the study of inhomogeneity probl ems of monolayers, which are very important for the application of suc h layers to optical and molecular electronic devices. In the discussio n, the feasibility of the application of the new optical-fiber sensor to the atomic force microscope is also analyzed.