Scanning optical microscopy with an electrogenerated chemiluminescent light source at a nanometer tip

Electrogenerated chemiluminescence at electrodes with effective diameters d own to 155 nm was used as a stable light source for near-field scanning opt ical microscopy imaging of an interdigitated array and a submicrometer size test substrate. Light was generated in a thin (similar to 500 pm) layer of an aqueous solution of 15 mM RU(bpy)(3)(2+) and 100 mM tri-n-propylamine i n a pH 7.5 buffer. The resolution obtained was compared to that found with a micrometer size electrode. The shear force from the tip attached to a qua rtz tuning fork was used to monitor and control the tip-to-substrate separa tion within the near field regime.