A novel cleaning method of gold-coated atomic force microscope tips for their chemical modification

For chemical modification of gold-coated AFM tips with thiol or sulfide com pounds, a new two-step precleaning procedure was studied. The two-step clea ning procedure involves (i) oxidation of organic contaminants on the AFM ti ps with ozone treatment and (ii) reduction of the oxidized gold surface by immersing the oxidized tip into pure hot ethanol at ca. 65 degrees C. The c hemically modified tips prepared from gold-coated AFM tips precleaned by th e two-step procedure gave almost the same tip characteristics as those chem ically modified immediately after gold vapor deposition in a factory. The p resent two-step cleaning procedure can be used widely for chemical modifica tion of commercially available gold-coated AFM tips with thiol or disulfide compounds for chemical force microscopy. (C) 2000 Published by Elsevier Sc ience B.V. All rights reserved.