Near-field fluorescence imaging and simultaneous observation of surface potentials

We present a new detection method to measure simultaneously surface potential and fluorescence intensity distributions using a combined scanning near-field optical microscope-atomic force microscope (SNOM-AFM). A surface potential image of phospholipid monolayers was obtained in non-contact mode using the SNOM-AFM with a thin-step etched optical fibre probe. For applying this technique, a phospholipid of dipalmitoylphosphatidylethanolamine labelled at the head with a nitrobenzoxadiazole group was used as a fluorescent and single component Langmuir-Blodgett film. It is well known that aggregation of the lipid molecules and their fluorescence intensities are very sensitive to its environmental conditions such as humidity and temperature. We demonstrated for the first time the near-field optical imaging and simultaneous observation of surface potentials with Maxwell stress microscopy.