NANOTRIBOLOGY - AN UHV-SFM STUDY ON THIN-FILMS OF C-60 AND AGBR

We performed scanning force microscopy (SFM) in ultrahigh vacuum (UHV) on C60 and AgBr thin films deposited on NaCl(001) substrates. The mor phology of the initial growth stage and the nanotribological propertie s of these thin films are characterized and discussed. A novel experim ental approach is presented where local friction coefficients are dete rmined: the lateral (frictional) forces are measured as a function of normal load, controlled by an external ramp generator. The local frict ion coefficient can be extracted by means of the two-dimensional histo gram technique. In the low load regime, friction coefficients of 0.15 +/- 0.02, 0.33 +/- 0.07 and < 0.03 were found between probing SiOx tip and C60, AgBr and NaCl, respectively. The two-dimensional histogram r eveals significant details about the force regime of wear-less frictio n and the initial stage of wear on these thin films.