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Abstract: Single-molecule force spectroscopy experiments, as well as a number of otherphysical systems, are governed by thermally activated transitions out of ametastable state under the action of a steadily increasing external force. Themain observable in such experiments is the distribution of the forces, at whichthe escape events occur. The challenge in interpreting the experimental data isto relate them to the microscopic system properties. We work out a maximumlikelihood approach and show that it is the optimal method to tackle thisproblem. When fitting actual experimental data it is unavoidable to assume somefunctional form for the force-dependent escape rate. We consider a quitegeneral and common such functional form and demonstrate by means of data from arealistic computer experiment that the maximum number of fit parameters thatcan be determined reliably is three. They are related to the force-free escaperate and the position and height of the activation barrier. Furthermore, theresults for the first two of these fit parameters show little dependence on theassumption about the manner in which the barrier decreases with the appliedforce, while the last one, the barrier height in the absence of force, dependsstrongly on this assumption.



Autor: Sebastian Getfert, Mykhaylo Evstigneev, Peter Reimann

Fuente: https://arxiv.org/







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