Breaking bonds in the atomic force microscope: Theory and analysis

Abstract

A theoretical framework is developed to analyze molecular bond breaking in dynamic force spectroscopy using atomic force microscopy. An analytic expression of the observed bond breaking probability as a function of force is obtained in terms of the relevant physical parameters. The force-ramp mode is discussed in detail, which gives the best framework to extract the relevant physical parameters such as the potential depth and its width, if a set of widely different force-loading rates are used. We also show that the commonly used Ritchie-Evans model is incomplete and that it is only applicable for forces well below the maximum permitted by the potential. Statistical complications arising from the use of constant velocity experiments are discussed in detail.