Abstract :
Self-assembled monolayers SAMs.on Au 111.were formed in vacuum by depositing nonanethiol molecules on a gold
substrate, and the resultant film was observed and modified using a scanning tunneling microscope STM.. The application
of voltage pulses of 2.6 V to the sample resulted in the local extraction of molecules from the film without causing serious
damage to the substrate and the molecules. The dynamic reformation process of the SAM film after the molecular extraction
was observed. An uncovered area of about 10 nm2 was almost recovered typically within several minutes, and the molecular
lattice was once again visible. This recovery process was suppressed during the period when the STM tip was detached from
the film surface, indicating that the extracted molecules were transferred to the tip surface, and that they returned as the tip
scanned over the uncovered area. A small number of defects that did not disappear were detected, suggesting that molecular
readsorption was prevented on the sites. q1999 Elsevier Science B.V. All rights reserved
