Scanning near-field fluorescence microscopy of a phase-separated hydrocarbon–fluorocarbon mixed monolayer

We previously developed scanning near-field fluorescence microscopy (SNFM) by combining SNOM and atomic force microscopy (AFM). We demonstrate that this combination can be used for fluorescence imaging and spectroscopy for a localized nanoarea. A small amount of a cationic cyanine dye with two long alkyl chains (CD) was added to see whether this hydrocarbon (HC) fluorescent dye is preferentially dissolved in the HC island phase in phase-separated mixed monolayers of HC and fluorocarbon (FC) amphiphiles. The SNFM image clearly shows that the modified SNOM–AFM can be used to observe fluorescence and topography images. The image also confirms the preferential dissolution of CD in the HC phase.