An Observation on Bell’s Model for Molecular Bond Separation Under Force

Abstract

Within the context of reaction rate theory, Bell proposed a particular dependence of the reaction off-rate on applied force to describe molecular bond separation under force. Here, the issue is re-examined from the point of view of the diffusive transport of bond states over a landscape of interaction energy for the bond pair in the presence of a time-dependent applied force. We are led to an expression for the off-rate which is perhaps more soundly based and which reduces to Bell’s result for bond separation at force levels that are small in a particular sense. For a given molecular bond, it appears that the condition of small force can be assured only under conditions of relatively slow loading of the bond.