Fig. 2.

Desorption force (Upper) and AFM tip position (Lower) versus time. The rate dependence is studied by the following modified experimental procedure: starting with a surface-adsorbed C₁₆ chain, the AFM tip is moved toward the surface at a rate of 1 μm/s (A), pulled away from the surface at a rate of 1 μm/s (B), held at constant height for 7 s, then moved toward (C) and away from the surface at a rate of 4 μm/s (D). The plateau forces in A, B, and C are comparable. Between C and D the force on the cantilever drops suddenly to zero because the peptide detaches from the surface.