Figure 3.

Definition and demonstration of the concept of intrinsic barrier width. Marcus-type analysis of the barrier widths. Left-hand-side reactions (i), (iii), and (v) have the same intrinsic barrier width, whereas right-hand-side reactions (ii), (iv), and (vi) all have a different common intrinsic barrier width. (a) The two reactions have the same intrinsic barrier height but different intrinsic barrier widths. (b) The barrier widths of the two reactions respond to the same thermodynamic driving force change at different sensitivities. (c) Because of a large thermodynamic bias, reaction (vi) has a greater intrinsic barrier width but a smaller actual barrier width than reaction (v).