The dynamics of the flip-flop motion of single buckled dimers on (100) were elucidated by locating the tip of a scanning tunnelling microscope over a single flip-flopping dimer, and measuring the tunnelling current. On the basis of a statistical analysis of the time trace, this activation energy (and the energy splitting between the 2 stable configurations of buckling) were estimated. A strong dependence of the dynamics of the flip-flop motion upon the local environment was found. The activation energy differed significantly (directly measured = 0.032eV, estimated = 0.110eV) for dimers in various domains.

Atomically Resolved Local Variation in the Barrier Height of the Flip-Flop Motion of Single Buckled Dimers of Si(100). K.Hata, Y.Sainoo, H.Shigekawa: Physical Review Letters, 2001, 86[14], 3084-7