Fig. 2.

Transitions on complex landscapes in force spectroscopy are generally not independent, because the force faced by the system in a given transition depends on the duration of the preceding transitions. (A) Under a time-varying force, is the transition over the second barrier on the potential in black equivalent to the transition on the potential in gray? (B) Force–extension trajectories generated on the black potential in A show overlap between the forces faced upon arrival into the second well and the forces at the escape from this well. The overlap (the region indicated by a brace between the two trajectories highlighted in black) is caused by the delay of the transition from the first well. (C) Rupture force distribution for the transition over the second barrier (black histogram) is markedly different from the distribution (gray curve) for this transition if it were independent from the transition over the first barrier. (D) Force-dependent rate obtained by transforming the black histogram in C via the single-barrier transformation differs from the rate obtained directly at constant force, indicating that the effect of the first transition on the second one is not negligible.