Nanoscale imaging of surface topography and reactivity with the scanning electrochemical microscope.

Over the last 2 decades, scanning electrochemical microscopy (SECM) has been extensively employed for topographic imaging and mapping surface reactivity on the micrometer scale. We used flat, polished nanoelectrodes as SECM tips to carry out feedback mode imaging of various substrates with nanoscale resolution. Constant-height and constant-current images of plastic and Au compact disc surfaces and more complicated objects (computer chips and wafers) were obtained. The possibility of simultaneous imaging of surface topography and electrochemical reactivity was demonstrated. Very fast mass transfer at nanoelectrodes allowed us to obtain high-quality electrochemical images in viscous media under steady-state conditions, e.g., in 1-methyl-3-octylimidazolium-bis(tetrafluoromethylsulfonyl)imide (C(8)mimC(1)C(1)N) ionic liquid. Ion-transfer-based imaging was also performed using nanopipets as SECM tips.